Extension talk:Scribunto/Lua reference manual

capital in Then
Re : "If named arguments to #invoke are specified, for example " is not a full sentence, so "Then" cannot be with a capital.--Patrick1 (talk) 11:44, 30 August 2012 (UTC)

pattern in which function ?
"the empty capture captures the current string position (a number)." Perhaps a note about "pattern " could be usefull in these functions ? --Rical (talk) 11:51, 23 December 2012 (UTC)
 * string.find (s, pattern [, init [, plain]])
 * string.gmatch (s, pattern)
 * string.gsub (s, pattern, repl [, n])
 * string.match (s, pattern [, init])

What's available on WMF projects?
It seems like a lot of the libraries mentioned in this manual are not available on test2.WP, which I assume means that they won't be available on the WMF projects that Scribunto is about to be deployed on? (For example,,  ,  , and   all appear to be missing.) Could this manual be edited to make clear which modules are available in what Scribunto versions? —Ruakh TALK 05:02, 18 February 2013 (UTC)
 * mw.ustring is available now. Here's a little test: User:Amire80/Scribunto. --Amir E. Aharoni (talk) 04:20, 19 February 2013 (UTC)
 * The hard part about that is idenfitying the versions. There isn't a 1:1 relationship between the version of MediaWiki and the version of Scribunto; for example, until the deploy 9 hours ago wmf9 had a relatively old version, which was upgraded to the newest. This could potentially be done again if warranted, rather than waiting for wmf11 to get the latest updates. Anomie (talk) 13:21, 19 February 2013 (UTC)
 * This is a point of confusion, though. As of right now there is no way to know for sure which functions are available on any given wiki, except by writing test code to see if it works or triggers a script error. At the very least, the documentation should specify the first Scribunto version for which each function became/will become available. CodeCat (talk) 22:19, 5 March 2013 (UTC)
 * Define "Scribunto version"; saying bit32 is first available in 5e548e769a464e3223cd52ffa0f819f6bf1c9924 doesn't help a whole lot. Anomie (talk) 02:34, 7 March 2013 (UTC)
 * It is possible to test existence of stuff by performing ~=nil tests. It is not very nice but it works (I use it in my test module to check functions that appears). Maybe we could write a "What's available module" that shows what is present or not? Hexasoft (talk) 08:59, 7 March 2013 (UTC)

(u)string patterns and PCRE
I believe, for people who know PCRE a special explanation of differences should be written, except that one must use  instead of. I was confused not to find  construction in Lua. Ignatus (talk) 15:16, 1 March 2013 (UTC)
 * Done. Anomie (talk) 17:10, 1 March 2013 (UTC)
 * Great! Ignatus (talk) 18:26, 2 March 2013 (UTC)

Split the page?
This page is very long right now. Should it be split into several subpages? I think splitting the general Lua documentation (which mostly just reiterates the official documentation anyway) from the Scribunto-specific stuff would be a good idea. So it would become Extension:Scribunto/Lua reference manual and Extension:Scribunto/Scribunto libraries or something similar. Actually... why is a separate documentation for general Lua even needed on this page if it's already available elsewhere? It might be more useful to note only the points where Scribunto differs. CodeCat (talk) 22:17, 5 March 2013 (UTC)
 * Documentation for general Lua is useful here to avoid people getting lost in BNF, to provide wikilinks to relevant articles, and to avoid people getting lost in the documentation for things that aren't available in Scribunto. Anomie (talk) 02:35, 7 March 2013 (UTC)
 * I agree with this point of view: easier for wikilinks, all is here, what's not in scribunto is not here. In addition some things are pure "Lua" and others pure "Scribunto", but some are Lua-but-changed-in-Scribunto. Hexasoft (talk) 08:48, 7 March 2013 (UTC)

Documentation question
Hello, Anomie: in the change you made today you added mw.language:formatDuration and lang:getDurationIntervals in two different places, but they both have the same parameters and the same description. Is it a copy/paste error or really two functions performing the same action? (in which case you may collapse the two sections in my opinion). Regards, Hexasoft (talk) 08:48, 7 March 2013 (UTC)
 * Eek. Don't bother. It's too early the morning, I don't read it correctly. Hexasoft (talk) 08:52, 7 March 2013 (UTC)

request for libraryUtils: new
i would like to see in libraryUtil a little syntactic sugar called "new", emulating a constructor, to help make lua a tiny bit more OO like. this will allow me, e.g., to do things like or to create a table with some members, some of which may be functions, and construct new "instances" of this table by calling "new" and the table:

peace - קיפודנחש (talk) 18:07, 11 March 2013 (UTC)
 * The usual idiom seems to be to use  rather than  . Also, due to Scribunto's sandboxing, it is not possible for a  d library such as libraryUtils to add global functions as proposed here; it would wind up as , at which point you may as well use the normal idiom. BJorsch (WMF) (talk) 13:19, 12 March 2013 (UTC)
 * regarding your 2nd comment: sure, i meant  (also changed the snippets above to reflect this more correct usage). not a problem.
 * however, my Lua-fu is not that strong, and i'm not sure i understand your "standard idiom" comment. calling  result in an error, as well as  . if you mean i should write a new "new" function in any table i want to construct, then yes, i understand this is possible, but i think what i ask is both more elegant and simpler, while suplying the reuired functionality. of course, it won't stop anyone from creating tailored constructors, and calling them "new" or "construct" or duplicating the object name, or any other name they choose. peace - קיפודנחש (talk) 17:55, 12 March 2013 (UTC)

mw.text.unstrip
Hello, as far as I understand the doc, the  function will allow to "unstrip" incoming strings that include tags such as nowiki. It is fine (I filled the bugreport) because it will allow to read the full content of any kind of parameters. My question: does using  on the unstrip string will produce the same original string? Also, to be sure: unstrip will returns a copy, not modify the original string?

Regards, Hexasoft (talk) 19:31, 11 March 2013 (UTC)
 * No,  on the unstripped string will expand any wikitext in that string. Even if you were to add back the correct extension tag (e.g. wrap the string in , or , or whatever), the result still might not be the same. For example,   might return , but then unstripping might result in  : the HTML for the superscripted footnote, which isn't even valid for return from the Lua module since  is not allowed in wikitext. It's even possible that the text hidden behind   is something completely unexpected such as serialized PHP data, as it may be that the extension is intending to do postprocessing in a ParserAfterParse hook or the like.
 * Yes,  does not modify the original string. Strings in Lua are immutable and primitive values are passed by value, so it is not possible to modify an input string in a normal function call (you can modify the keys/values in an input table, of course). BJorsch (WMF) (talk) 13:38, 12 March 2013 (UTC)
 * Thanks for the clarification. I will play with it when available. Regards, Hexasoft (talk) 17:58, 12 March 2013 (UTC)

In section "mw.language:formatDate"
Hello, in section Extension:Scribunto/Lua reference manual it is said: « Formats a date according to the given format string. If  is omitted, the default is the current time. The value for  must be a boolean or nil; if true, the time is formatted in the server's local time rather than in UTC. » Rather than « server's local time » shouldn't it be « wiki local time »?

Regards, Hexasoft (talk) 16:39, 17 March 2013 (UTC)
 * Yes, it should be. Thanks for pointing out the error. BJorsch (WMF) (talk) 23:10, 17 March 2013 (UTC)
 * I just noticed some similar language in the os.date section. I assume this should also be wiki time, rather than server time? — Mr. Stradivarius  ♪ talk ♪ 10:52, 3 February 2014 (UTC)
 * os.date is a Lua builtin and really does use the server's local time. You can test this easily enough by going to dewiki or another wiki with a non-UTC local time set, edit any module page to get to the debug console, and compare the output of  versus  . Anomie (talk) 14:12, 3 February 2014 (UTC)

Suggestion for mw.text: word distance
Hello, I had the need of a distance function beetween words, and coded en:Levenshtein distance in my module. Don't know if it should be useful (I see few cases where that feature can be useful) but if you think it is it could have its place in mw.text module. Moreover I think it is the kind of algorithm that can be far more efficient in something else than Lua (I guess that a double-looping on characters from two strings is − for example − far more efficient in C or any language that gives direct accès to string elements).

Regards, Hexasoft (talk) 17:21, 21 March 2013 (UTC)
 * There are a lot of things that would be easier done in PHP, but on the other hand we don't want to bloat the Scribunto libraries with too many features that won't be of general use. On this one, I'd personally lean towards "no". But if someone else wants to code it up and put a patch in Gerrit, they can and we'll see what anyone else things. BJorsch (WMF) (talk) 13:28, 22 March 2013 (UTC)

environment for getfenv(function)

 * We can read : "Passing a function returns the environment that will be used when that function is called."
 * Can we say : "Passing a function returns the environment where this calling function is, if any, else nil. In case of recursive function, returns the nearest call of this function." ? --Rical (talk) 18:40, 21 March 2013 (UTC)
 * That would not be accurate. All functions have an environment, it's just that Scribunto may restrict access to some of them. And the environment returned depends on the function, not on the call stack; the "environment" returned is usually the same table that function sees as . BJorsch (WMF) (talk) 13:38, 22 March 2013 (UTC)

Conditionals
The reference doesn’t formally cover if-then-else conditionals. —Michael Z. 2013-03-21 21:55 z 
 * Extension:Scribunto/Lua reference manual seems to cover it. BJorsch (WMF) (talk) 13:39, 22 March 2013 (UTC)

mw.text.tag request
So there is one special property for tags, also known as "style". jQuery acknowledge this, so setting style elements is not done through calling elem.attr('style', something) (although this will also work), but rather, they provide a special api called elem.css.

so here is the request: to provide some mw.text.XXX support for style. this can be done either by augmenting the ma.text.tag somehow, or by creating a whole new mw.text.style(...). if the latter approach is taken, i'd like to make a suggestion: please allow for multiple parameters, and concatenate them using semicolon. so the call should look something like so: this is not meant to be the code itself, necessarily - clearly i did not think of all the possible implications. it's more of a sektch to illustrate the required functionality of helping the lua programmers composing "style" attribute from different bits and pieces of flotsam. either way, some functionality that would best mimic jQuery's ".css" would be greatly appreciated. peace - קיפודנחש (talk) 15:40, 30 March 2013 (UTC)

Fragment
The arguments for  are. Namespace, title, and interwiki are familiar enough to me, but what does fragment mean? Does this refer to the project link? I assume, for example, that the "fragment" in  would be "wikt". Is this correct? — Mr. Stradivarius  ♪ talk ♪ 11:19, 3 April 2013 (UTC)
 * Ah, I see I was wrong after playing around with this for a bit. It seems the fragment is the part that appears after "#" in the URL, and that the "interwiki" part includes both the project name and the language name. If no-one has any objections, I think I'll update the manual to say this. — Mr. Stradivarius  ♪ talk ♪ 12:32, 3 April 2013 (UTC)
 * Feel free. Note that "fragment" (or sometimes "fragment identifier") is the actual name for that part of a URL, see RFC 3986 § 3.5. Anomie (talk) 13:37, 3 April 2013 (UTC)

Access to MediaWiki API; access to page text
Hi. I have two somewhat related questions.


 * 1) Is there any ability currently to access the MediaWiki API from Scribunto? For example, I'd like to get a list of all the subpages of Global message delivery/Targets. This is available in the MediaWiki API, but I'm not sure if Scribunto can retrieve this information right now. It'd be super-helpful to have a Special:PrefixIndex equivalent available (or more generally, access to the MediaWiki API).
 * 2) Is there any ability currently to access page text? For example, I want to count instances of a string within the wikitext of Global message delivery/Targets/Wikidata.

Thanks in advance for any help or pointers here. --MZMcBride (talk) 18:03, 4 April 2013 (UTC)
 * Hello,
 * I can answer to the #2 question: title objects has a getContent method, allowing to get the raw content of the page corresponding the the title object. See Extension:Scribunto/Lua_reference_manual (the last entry). It think it is what you are looking for. Regards, Hexasoft (talk) 19:18, 4 April 2013 (UTC)
 * PS: note that I read somewhere that a Scribunto library exists (or is planed) to access wikidata stuff. Not sure about how advanced it is.
 * note that title object in general, and getContent in particular, do not work for titles on another wiki/site, so if the requirement is, for instance, to get the content of Global message delivery/Targets/Wikidata from any other wiki than meta, it won't help you, and i do not think this is possible. peace - קיפודנחש (talk) 22:37, 4 April 2013 (UTC)
 * The Wikibase Lua API will be deployed as the same time as the #property parser function. So, next Monday for en Wikipedia and, if all is good, Wednesday for the others. Here is the doc. I've already written [//test2.wikipedia.org/wiki/Module:Wikidata a module to test it]. Tpt (talk) 20:05, 5 April 2013 (UTC)
 * Making arbitrary API queries from Scribunto is probably not going to happen; they would be slow and prone to issues with proper data sanitization and accounting of the CPU time. This was discussed in this wikitech-l thread. BJorsch (WMF) (talk) 13:30, 5 April 2013 (UTC)
 * All right. So for the Special:PrefixIndex example mentioned above, how would I achieve this functionality? File a bug in Bugzilla about adding this functionality to Lua/Scribunto? Will I need to do this for each MediaWiki API feature I want ported over to Scribunto/Lua? (Generating input lists seems like it'll be a pretty commonly needed functionality inside Scribunto modules, to avoid duplicating/hardcoding lists of pages, templates, transclusions, categories, images, external links, etc.) --MZMcBride (talk) 18:33, 7 April 2013 (UTC)

Links related to this discussion:


 * wmf:Module:Count
 * m:Module:Count
 * 47137

Perhaps these will be helpful to someone. --MZMcBride (talk) 20:48, 11 April 2013 (UTC)


 * Actually, you can transclude and unstrip Special:PrefixIndex - see w:Module:Module overview for an example. A problem though is that I found out this causes the cache to be disabled, so the page is regenerated on every view.  On the other hand, you can use the mw.message library to link to the such an uncacheable page, and then the page will never be updated except when it is edited.  Alas, I still know of no way to say refresh the cache once a day or once a week.  (Speaking of which I never did remember to update Module Overview to avoid reloads, hmmm... Wnt (talk) 05:54, 24 January 2014 (UTC)
 * And only limited number of subpages is processed. See also category handling by Lua: ru:module:category. Ignatus (talk) 16:00, 24 January 2014 (UTC)

System messages with "page" or "subpage" ?
Hi.

Do you know what's the diffrence between messages system like Mediawiki:Scribunto-doc-subpage-xxx and Mediawiki:Scribunto-doc-page-xxx ? It seems that the twice exist.

Thanks by advance for your answer, Automatik (talk) 14:53, 5 April 2013 (UTC)
 * "Mediawiki:Scribunto-doc-subpage-xxx" was renamed to "Mediawiki:Scribunto-doc-page-xxx". The former is no longer used. BJorsch (WMF) (talk) 21:16, 6 April 2013 (UTC)
 * Thanks! Automatik (talk) 00:55, 7 April 2013 (UTC)

Extension for mw.text.listToText
Hello, it may be usefull to add the possibility to add something before/after items given to. I.e. something like ... or why not ... so that it would not need to preprocess incoming parameters just to add constant strings before/after them before passing them to.

Maybe something like an optional  parameter (i.e. " %s ", or optional pre and post parameters).

Regards, Hexasoft (talk) 21:50, 6 April 2013 (UTC)
 * Hmmm… Well, in fact it can be simulated by:
 * . The only problem is that it prevent using the default separators. Regards, Hexasoft (talk) 08:55, 9 April 2013 (UTC)
 * Yes, I also would like to use %1..9 in the string formats, example:  like in , with a last string format for the last element, and another string format for all other before elements. --Rical (talk) 11:09, 9 April 2013 (UTC)

mw.language:parseFormattedNumber
Documentation says:

This takes a number as formatted by lang:formatNum and returns the actual number. In other words, this is basically a language-aware version of.

However, if you call, you will not get nil as expected (after all, this is what tonumber returns), but rather 'bla bla bla'. i'd rather you fix the code to do what the documentation implies rather than fix the documentation to say what the code currently does, so i did not touch the documentation. however, i recommend that until this is fixed, we should use  if we really wand "tonumber" behavior. peace - קיפודנחש (talk) 17:25, 12 April 2013 (UTC)
 * Anomie (talk) 00:56, 16 April 2013 (UTC)

File information
Is it possible to add file dimensions to the title objects? Is this even the right place to ask? — 69.162.8.80 17:47, 12 April 2013 (UTC)
 * Better would be bugzilla. Anomie (talk) 00:43, 16 April 2013 (UTC)

Debug console
Hi,

When we edit a module, we can see below the interface edition the debug console where it's written:

«* Precede a line with "=" to evaluate it as an expression, or use print.»

But the function print is not available. How to change this text (in all languages)?

Thanks by advance, Automatik (talk) 21:01, 14 April 2013 (UTC)
 * It works fine for me. Something like  prints whatever the   function returns, same as   does.   doesn't do anything in the module itself, but you can use it in the debug console—at least on en.wikipedia. — 69.162.8.80 20:32, 15 April 2013 (UTC)
 * Yes,  is available as an alias for   in the console only. See Extension:Scribunto/Lua reference manual. Anomie (talk) 00:41, 16 April 2013 (UTC)
 * it would be nice if we had the debug console in Special:TemplateSandbox, to get the output of all the modules. is it possible to expand the synergy between Extension:Scribunto and Extension:TemplateSandbox as to include scribunto debug console in the sandbox? it would be nice, of course, to do it in the most generic way possible, so if sandbox will learn to do its thing with other extensions, they will be able to hook *their* debug console to the sandbox too. peace - קיפודנחש (talk) 22:02, 19 April 2013 (UTC)
 * I've been working on including the mw.log output in all page previews. But it's currently hung up on a tangential UI change that I haven't had time to get to. BJorsch (WMF) (talk) 12:58, 22 April 2013 (UTC)
 * Thanks. i think it will be very useful. peace - קיפודנחש (talk) 21:52, 22 April 2013 (UTC)


 * I dont understand how to use the debug console. There's only input field and one button "clear". How to know value of variables/functions from text of script? If I type "=variable" in the field - nothing changes. If I insert mw.log or mw.log (variable) in script - also nothing. --Vladis13 (talk) 23:44, 18 November 2015 (UTC)

argument to
What does it do? Seems like nothing, in console  gives the opened module name, not "Ignatus". Well, it would be great if someday we could expand templates like on a page with specific title. Ignatus (talk) 08:17, 16 April 2013 (UTC)
 * It sets the title of the new frame. But at a glance, I don't see anything that actually uses the frame's title ( gets the title of the page being parsed from the parser). Anomie (talk) 12:48, 16 April 2013 (UTC)

mw.text.unstrip: be able to detect wiki tag?
Hello, the  will be useful for some cases where we get parameters in nowiki tag is some cases. But is there a way to know that a string is "tagged" and/or to know with which tag(s)? Of course comparing str with unstrip(str) can do it for the first point but it is not very nice, and it don't allow to know which kind of data is inside (I mean, nowiki or pre should be fine 'cause data inside is « real », ref is probably not fine − [1] is not treatable).

Regards, Hexasoft (talk) 13:34, 30 April 2013 (UTC)
 * You can extract the tags that  replaces with a pattern something like  . Often a pattern like   should give you the name of the tag too, but that's not guaranteed to work. Anomie (talk) 13:00, 1 May 2013 (UTC)
 * Yes. When I played with stripped strings I found this point. As internal strip structure is internal maybe a mw.text.isStripped(text) that whould return nil or a string with the tag found? (or to make unstrip returning a second argument with the same convention?)
 * It is clearly not difficult to code this by myself. It would be useful if the internal structure may change in the future. If not it is not an important point.
 * Thanks, Hexasoft (talk) 08:33, 22 May 2013 (UTC)

mw.ustring.isutf8
Hi,

Is it normal that I get  when I call a function who returns   ? How to understand what a utf8 character is?

Thanks by advance, Automatik (talk) 01:56, 2 May 2013 (UTC)
 * Yes, because that string is valid UTF-8. You would get false for something like  because a byte 128 may not follow a byte 48 in a UTF-8-encoded string. See UTF-8 (or, as I see you edit most on French-langauge projects, UTF-8) for details on UTF-8 encoding. Anomie (talk) 13:15, 2 May 2013 (UTC)

metamethod
Is it planned to use it for overriding # operator? I see it is highlighted in edit window like others but doesn't yet work. Ignatus (talk) 11:41, 16 May 2013 (UTC)
 * The __len metamethod does not apply to tables in Lua 5.1, which Scribunto is based on. If there is a way to simulate it in pure Lua 5.1 (i.e. without recompiling or loading C libraries), we'd be very interested. Anomie (talk) 13:27, 16 May 2013 (UTC)
 * It is possible to get that behaviour using proxies. It is possible to create a light userdata with, whose   metamethod is called when the   operator is used. Example:


 * A safe version of  could be provided: check that you're not setting the metatable of a core object, like strings, numbers, booleans or nil.


 * ... but Scribunto backports __pairs and __ipairs from Lua 5.2.. Why isn't __len for tables supported as well? I don't think it it would break any existing code, since  is currently useless if you don't want the default behavior. -- Pygy 81.243.36.191 11:55, 3 June 2013 (UTC)
 * Hmm, undocumented, which seems to have been removed entirely in 5.2. I'll have to have a look at that at some point, to see if it seems close enough to a real table to be usable internally (e.g. for  ).   may turn out to be troublesome. But at a glance I doubt we'll want to expose   and even a wrapped   to module code.
 * We can backport __pairs and __ipairs because doing in in pure Lua just requires redefining pairs and ipairs using documented and supported methods; see . Anomie (talk) 14:38, 3 June 2013 (UTC)
 * was experimental and it was removed because its primary use case (the custom  metamethod) was no longer needed in 5.2.   returns  . The  patch that backports len is rather short (https://github.com/dubiousjim/luafiveq/blob/master/patches/table-len.patch)... Why are you reluctant to use a patched version? BTW, if you are using LuaJIT, enabling   is one compile-time switch away. Edit: my bad regarding LuaJIT: the flag I mentioned also enable a slew of other Lua 5.2 features, and removes two methods from the standard lib... That being said, the functionality is already there, it must just be enabled. -- Pygy 81.243.36.191 22:46, 3 June 2013 (UTC)
 * Because we want other wikis to be able to use Scribunto without installing custom binaries, which their hosting provider may not even allow. At one time even requiring the stock Lua interpreter was worrisome. Anomie (talk) 13:51, 5 June 2013 (UTC)
 * That makes sense, I'm not familiar with the distribution process of MediaWiki. If I understand you properly, providing patched Lua source and binaries along with MediaWiki is not an option, then... -- Pygy 89.90.144.90 08:50, 10 June 2013 (UTC)
 * It turns out that debug.setmetatable is not needed:


 * -- Pygy

Please tell something more about frame:getParent
frame:getParent Called on the frame created by, returns the frame for the page that called. Called on that frame, returns nil.

Very exoteric doc.... :-D  I couldn't understand what it means; but, while browsing some script into fr.source, I found (if I'm not wrong) that this is the key to pass arguments from a template to a Lua script, and this is mostly important (see s:fr:Module:Table. Can someone expand doc as it deserves? Thanks! --Alex brollo (talk) 07:59, 23 May 2013 (UTC)
 * Hello,
 * the frame is the "environment" of the caller. This environment (mainly) includes the agurments given to the call (the #invoke). As modules are often called from a template, which is used in articles, the arguments given to the template are not in the frame but in the getParent of the frame. Let give an example:
 * In article foo we call . This template do:.
 * In the function myfunction from module Module:Mymodule if you read the arguments in  you will find modulearg1 and modulearg2 as unamed arguments. If you access the args table of the parent frame (using  ) you will find templatearg1 and templatearg2 as unamed arguments.
 * Of course if you directly use a module with #invoke rather than with an intermediate template only the main frame exists.
 * Hope it will help you.
 * Regards, Hexasoft (talk) 08:20, 23 May 2013 (UTC)
 * Thanks! I'll test into my sandbox. I guess, from fr.source script, that I can retrieve templatearg1 and templatearg2 by   even if template doesn't pass parameters explicitely when calling the module (a statement   is sufficient). Well, I've what I need to learn by "try and learn". --Alex brollo (talk) 10:03, 23 May 2013 (UTC)
 * It runs :-) --Alex brollo (talk) 13:18, 23 May 2013 (UTC)

Also beware that neither frame:getParent nor frame.args ever return the intermediate args.
 * In article foo we call.
 * The template mytemplate has the code
 * The template myothertemplate has the code

Module:mymodule will never get templatearg3, templatearg4 unless you specifically pass them from the last (myothertemplate) to the module. You should use something like  (or some other code that checks the existence of these parameters before passing them to the module, not very practical though)--Xoristzatziki (talk) 10:29, 9 August 2018 (UTC)
 * You seem to have that backwards.  is specifically intended to return your templatearg3 and templatearg4. Anomie (talk) 12:08, 9 August 2018 (UTC)

mw.language:formatNum in the Lithuanian
In the Lithuanian number 123456.78 must be given as "123 456,78". but result is "123&#nbsp;456,78". --Vpovilaitis (talk) 05:09, 24 May 2013 (UTC)
 * It works fine for me:  returns "123 456,78", with a raw non-breaking space character. Whatever you're using to encode html entities appears to be mis-encoding the non-breaking space as "&amp;#nbsp;" rather than "&amp;nbsp;". Anomie (talk) 07:17, 24 May 2013 (UTC)
 * Thanks. I'm experiment with en:Module:Chart. But this text was in tooltip (title tag). --Vpovilaitis (talk) 08:03, 24 May 2013 (UTC)

I'm lazy, so I'm going to suggest...
Could there be another set of classes added: Just an idea to enable my laziness... :p Technical 13 (talk) 17:08, 7 June 2013 (UTC)
 *  : represents all magic characters.
 *  : All characters not in.
 * Not likely. We don't want to mess around with extending the standard Lua methods like, and we don't want to take the   methods too far from the corresponding   methods.
 * Also, what would be the point of this? The only thing I can see that it might be useful for is if you were trying to escape a user-supplied value-that's-not-supposed-to-be-a-pattern, but for that you can just use  because all magic characters are in %p and anything in %p that isn't magic will still work properly when escaped. Anomie (talk) 15:08, 8 June 2013 (UTC)

String methods
The manual says that when we call a method on a string, we are using the string library. So in the above code, we would be calling the function. However, it also says that using the string library cannot operate on unicode characters, and that we should use the mw.ustring library instead. For this reason, is using string methods a bad idea? I have noticed a few places that they are used in code already, and I am curious. — Mr. Stradivarius  ♪ talk ♪ 08:51, 12 June 2013 (UTC)
 * Personally, I try to avoid it in Scribunto code for that reason. Although if you are doing bytestring manipulation, the ability to chain calls is useful. But IMO that's a matter for a style guide rather than the reference manual. Anomie (talk) 12:59, 12 June 2013 (UTC)
 * That's what I thought - thanks for the clarification. I guess I'm new to issues of coding style - such things didn't really exist (?) with template code. — Mr. Stradivarius  ♪ talk ♪ 12:18, 20 June 2013 (UTC)

mw.ustring library missing reverse method

 * The following discussion is closed. Please do not modify it. No further edits should be made to this discussion.

this may seem as a useless method, but it's not: specifically, Extension:EasyTimeline, which is installed on wikimedia wikis, treat all strings as if they were written from left to right. this means that for RTL strings, we need to reverse them manually, which was a major point of frustration for Timeline users on RTL wikis. i can't think of a good reason why mw.ustring should omit to provide the standard string function. peace - קיפודנחש (talk) 13:57, 15 June 2013 (UTC)
 * Because correctly reversing a Unicode string is non-trivial. You can't just reverse the codepoints, you have to divide the string into "abstract characters" (base characters plus any combining characters) or "grapheme clusters" and reverse those. And then you probably have to handle ties, bidi characters, and other such specially. Rather than trying to hack around it with Lua, it would probably be better to fix RTL support in Extension:EasyTimeline. Anomie (talk) 13:13, 17 June 2013 (UTC)
 * in principle i think you are correct, but in reality, it would be useful to have a reverse function with a footnote, explaining that this function actually reverses codepoints and not "abstract characters". true, there would be cases where this limitation would make reverse useless, or at least "less useful", but i can't see how the current state of affairs, with no "reverse" at all, is any better. for hebrew, at least (and i believe the situation is very similar for arabic), these "abstract characters" appear when the string uses something callsed Niqqud. this is optional, and telling the users "do not use niqqud in such and such situation" is far superior to telling them "if you want to use timeline, you have to supply the strings backwards", which is what happens now (and, btw, i do not think niqqud works with timeline anyway).
 * as to the "Rather than trying to hack around it with Lua, it would probably be better to fix RTL support in Extension:EasyTimeline": this problem plagued the use of "timeline" in RTL wikis for years and years (ever since timeline was introduced - i think around 2005 or maybe even earlier). it was not fixed in the years since then, and is not likely to be fixed ever.
 * Lua gave us a nice opportunity to work around the issue (i actually already implemented string reversing on hewiki, by utilizing mw.text.split, manually reversing the table, and then use table.concat. i just thought that since lua supports string.reverse, we should also have mw.ustring.reverse ).
 * peace - קיפודנחש (talk) 16:00, 17 June 2013 (UTC)
 * Both of you are wrong. Unicode "code points" and "abstract characters" are exactly the same (except for special code points not assigned to abstract characters: the 4096 surrogates and the ~50 non-characters like U+FFFF).
 * The correct term is "combining sequences" (that are easy to split, and locale-independant) or the longer "grapheme clusters" (Unicode provide some data for them, but they are locale-dependant).
 * "Reversing a string" anayway is not an operation that should depend on locales as it will always create something that has no meaning in all locales (so "grapheme clusters" are not relevant at all).
 * What this means is that the reverse method can safely be implemented by splitting on boundaries of combining sequences (Bidi properties also do not matter at all!). It also does not matter if that string is not displaying the same clusters (when rendering this text that has no meaning).
 * All that is needed is to parse code points (their limits are extremely easy to detect, and the Ustring module already does that) and know if a codepoint is combining or not (i.e. its combining class is non-zero) to detect the boundaries of combining sequences (and to ensure that the result will respect canonical equivalences). You actually don't need a large map of exact combining classes but only if it is zero or not and the UCD provides a convenient "derived" data file for that (which is used by NFC/NFD normalizers).
 * In summary, the "Ustring" library should be able to return not just one code point, but should be able to easily parse and return combining sequences (even, if it does not support for now their normalization to NFC or NFD or NFKC or NFKD, something that requires more data: normalization to NFC would however be very useful).
 * I could create a demonstration of that, in pure Lua, and it will be fast, but this reverse function will be a "conforming Unicode process" and it will also be autoreversible (if it does not normalize its input or output, something that is not necessary).
 * It is even possible to implement it without using the "Ustring" code point parser, by working directly at the byte level with Lua "string". For example it is possible to create a pattern for gsub that will match a valid UTF-8 encoded combining character, and a second pattern that will match any other valid code point which is not a combining character or any other byte that cannot be part of a valid UTF-8 encoded character. Then use these two patterns (generated automatically from the small list containing all ranges of codepoints that are assigned to characters with a non-zero combining class) in a simple loop, to split an input string into a sequential table, that will then be reversed in situ, and then concatenated.
 * If you are still not convinced that the list of code point ranges is small, look at "http://unicode.org/Public/UNIDATA/extracted/DerivedCombiningClass.txt" (drop the part related to characters with combining class zero, merge the other lists per combining class into a single one) or at "http://unicode.org/Public/UNIDATA/DerivedNormalizationProps.txt" (look for NFC_QC or NFC_QD properties): in fact all we need is even smaller that these lists of ranges! Verdy p (talk) 20:59, 23 April 2015 (UTC)
 * You are wrong, an abstract character may be represented by multiple codepoints and thus they are in no way the same. And the reversing is more complicated than just looking for combining characters, see for the actual specification. It's possible to do, but it would take a large additional data table (from ). Anomie (talk) 22:20, 23 April 2015 (UTC)
 * No you are wrong. Per Unicode definition, an "abstract character" is definitely NOT a "grapheme cluster". Reread the standard itself (notably the "Unicode character model", published many years ago).
 * Code points are being assigned ONLY to abstract characters, or to non-characters (including surrogates), and an abstract character can be given ONE and ONLY ONE code point.
 * You are confused by the fact that "character sequences" may be standardized with a standard name by listing the code points to which it is mapped. But character sequences are also not necessarily combining sequences (it may contain several combining sequences) and they are also not necessarily grapheme clusters (because they are extensible by appending more combining characters and/or "grapheme extenders"). Unicode in fact does NOT standardize grapheme clusters (because they are locale-dependant), but ONLY "default grapheme clusters" (which are locale neutral but have little use, except in neutral locales such as the CLDR root).
 * In other words, you have absolutely no knowledge of the Unicode terminology (as a member and participant of Unicode since many years, I know that you're wrong, and that you have never read correctly this essential part of the standard). Verdy p (talk) 23:36, 26 April 2015 (UTC)
 * Quoting §3.4 D7, "Abstract characters not directly encoded by the Unicode Standard can often be represented by the use of combining character sequences." I can't see any way to claim that abstract characters and code points are the same thing, as you did above. I never said that an abstract character is the same thing as a grapheme cluster, but for properly reversing a string you'd likely need to consider grapheme clusters rather than abstract characters. Anomie (talk) 13:41, 27 April 2015 (UTC)
 * By definition, in Unicode itself, ALL abstract characters encoded in Unicode have a single (and warrantied) assigned code point; code points may also be assigned to "non-characters" (e.g. surrogates that don't even have a scalar value, or U+FFFE and U+FFFF which ARE valid code coints with a valid scalar value, but are not characters at all).
 * Once again reread the Unicode standard. The "combining character sequences" are still not defined by Unicode as "abstract characters" (the standard says that this interpretation **may** be done, but this is not what Unicode defines: the "combining character sequences" are NOT abstract characters encoded by Unicode. And they are also not code points, have no scalar values themselves. They are also NOT "grapheme clusters". The set of "grapheme clusters" (not defined by Unicode) includes the set of "combining character sequences" (defined by Unicode) which themselves includes the set of "abstract characters" (encoded by Unicode).
 * Other non-Unicode standards (which are also NOT standards supported by ISO 10646 in its version since 2003) are used to create more "abstract characters" (e.g. the Apple logo in MacRoman, or characters assigned in planes higher than plane 16, defined on the old UCS-4 encoding of the former ISO 10646:2000 standard), but there's no way to encode them uniquely with any standard Unicode encoding form (because Unicode does not assign tham any scalar value and does not allow to encode them either with the "combining sequences" defined by Unicode).
 * Unicode expressively says that ANY sequence of abstract characters encoded by Unicode is a VALID Unicode text (even if they don't make sense with some "grapheme clusters" that Uniucode does not define as they make sense only on specific locales and Unicode does not standardize languages, or orthographic conventions; note that Unicode defines only a subset known as "default grapheme clusters", but still they are not associated to any specific language or orthography, and in fact these "default grapheme clusters" are now mostly abandonned and were not made any entry in the standard or in standard annexes, but only in some informative technical annexes, and based on informative, non-normative character properties or other mutable rules of these technical annexes that are just documenting some of the known best practices). So there's NO "grapheme cluster" defined in the standard.
 * So I absolutely don't see why "ustring.reverse" cannot do what it is intended for: reverse the order of characters. It does not matter at all if this breaks some "grapheme clusters" defined for some languages, because the result will still be perfectly VALID Unicode text ! Of course you won't see the usual creation of clusters made in fonts (e.g. the joining of Arabic characters will have curious artefacts, or mutliline text will have the lines reversed), but still it renderers will still be able to render the generated pseudo-text correctly (and all these effects also exist with the "string.reverse" function (e.g. it will also reverse the order of lines, or will reverse CR+LF sequences to LF+CR).
 * So actually "string.reverse" is not made to create "meaningful" text, and the same can be said about "ustring.reverse" for exactly the same use.
 * There's no point in those two functions to speak about "grapheme clusters" when "string.reverse" already splits and reverses the CRL+LF "grapheme cluster" and reverse('text') returns 'txet' which has no meaning (in English), or reverse('chat') returns 'tahc' which also breaks the English cluster 'ch'.
 * Lua, or MediaWiki, do not even know what encoding or orthography or language is used in text, so they cannot infer any "meaning" of their sequences as their locale-sensitive "grapheme clusters", because their meaning or usage is completely opaque. As well, string.reverse('sample\000') returns '\000elpmas' which would break an interpretation as a null-terminated string like in C (it would be interpreted as an empty string), but this does nit matter: we are not concerned by string usages or interpretations in specific locales or environment that have their own requirement about their supported "grapheme clusters" (the valid Lua '\000' string is not a grapheme cluster in C, as a grapheme cluster can never be empty; but it is still a valid single "character" in C).
 * Lua or MediaWiki does not need then to know the "meaning" as "grapheme clusters" in "mw.ustring" or if it will render as expected.
 * But the generated strings won't create any conformance bug, they are valid, encodable, and fully supported as well by HTML if the original string is supported (original strings are supported only if they use a known subset of valid characters assigned to a wellknown set of code points, which includes MOST codes points that were either assigned to characters by Unicode, excluding MOST C0 and C1 controls, but also include other valid codepoints still not assigned, codepoints assigned to private use characters in the 3 PUA blocks, but does not include any code point assigned to "non-characters" like surrogates and U+FFFF; this set of valid codepoints is known, static, will never change, and any text using these codepoints is VALID in Unicode, and as well in HTML).
 * As well the combining sequences may be "altered" by normalization, but: normalization1(text)==normalization1(reverse(normalization3(reverse(normalization2(text)))) is still true even if the three normalizations here are different and order/combine/uncombines characters differently or one of them does nothing (provided that each normalization used is a "conforming process", which is the case for the four standard normalizations NFC, NFD, NFKC, NFKD, but which is not if it transcodes via another encoding, including with ISO 2022 variants, GBK, HKCS, SJIS, and even GB 18030) !
 * So reversing a text and reversing it again will preserve the canonical equivalence, and the "reverse" operation is then a "conforming" process according to the Unicode standard. Verdy p (talk) 19:30, 25 October 2018 (UTC)
 * The truth is that we need a mw.ustring.reverse function NOT to create meaningfulful text, but precisely to correctly and easily parse some Unicode texts (given the various limitations of Lua patterns, notably for unsupported alternation with '|' or unsupported bounded repetitions). Reversing UTF-8 strings has exactly the same uses as with ASCII-only strings. And it is always reversible again to recreate meaningful text.
 * But using "string.reverse" on UTF-8 text is NOT conforming as it breaks in the middle of encoded characters.
 * Permitting "string.reverse" in Scribunto for MediaWiki makes no sense at all, it should not even be tolerated and it should return an error instead, as it creates text that cannot be parsed as valid HTML !). There's no such risk with "mw.ustring.reverse" (which is extremely simple to implement reliably and efficiently, without needing to use costly splits/joins via large arrays, and without excessive use of the memory allocator and garbage collector if this is done only in pure Lua, where strings are immutable, but it is possible in pure PHP within Scribunto itself, which can also use the exposed PHP API of Mediawiki or one of its extensions, where some functions are implemented in native C libraries interfaced with PHP, including the Scribunto extension for Mediawiki (written in PHP but using a native C library to run Lua: PHP makes the link between native C, the Mediawiki API in PHP, and Lua where Scribunto exposes some "mw" packages).
 * Note: "mw.ustring.reverse" can be implemented efficiently (in pure Lua running within Scribunto) by:
 * applying "string.reverse" to the whole input string;
 * applying "string.gsub" with a pattern matching '[\128-\191]+[\194-\244]' (which detects ALL valid original UTF-8 sequences which were reversed by the 1st operation and became invalid) and substituting each match individual occurence with the "string.reverse" function. (This pattern matches a bit more than valid UTF-8 sequences only, and matches some invalid UTF-8 sequences, but only those found in input texts that were already not valid UTF-8)
 * These two successive operations may be made in any order (this does not change the result).
 * For example, with invalid UTF-8 input text:
 * mw.ustring.reverse('\129\128') will first reverse it completely to '\128\129' in the first operation, and the second operation will do nothing else, and you get '\128\129' which is also invalid text (reapplying mw.ustring.reverse will restore the original)
 * mw.ustring.reverse('\128\129\194') will first reverse it completely to '\194\129\128' in the first operation, and the second operation will match nothing, and you get '\194\129\128' (reapplying mw.ustring.reverse will restore the original, as in the following example)
 * mw.ustring.reverse('\194\129\128') will first reverse it completely to '\128\129\194' in the first operation, and the second operation will match everything to reverse it again, and you get '\194\129\128' (like the original)
 * mw.ustring.reverse('\194\128\194\129') (valid input) will first reverse it in the first operation completely to the (now invalid!) '\129\194\128\194', and the second operation will match '\129\194' and '\128\194', will reverse them separately, and you get valid output '\194\129\194\128' (reapplying mw.ustring.reverse will restore the original as in the following example)
 * mw.ustring.reverse('\129\194\128\194') (invalid input) will first reverse it completely to '\194\128\194\129' (now valid!) in the first operation, and the second operation will match nothing to reverse, and you get the valid ouput '\194\128\194\129' (reapplying mw.ustring.reverse will restore the invalid original)
 * In summary:
 * with any valid UTF-8 input, the result is also valid UTF-8, and reversible again by the same function.
 * with any invalid UTF-8 input, the result is also invalid UTF-8, and reversible again by the same function.
 * Applying once again the same two operations (also in any order) is then warrantied to return the initial input text, so "mw.ustring.reverse" is self-reversible.
 * with any valid Unicode text (which is valid UTF-8 and does not contain any non-character), the result is also valid Unicode text (and valid UTF-8), and reversible again by the same function.
 * with any invalid Unicode text (which is valid UTF-8 but contains one or more non-characters), the result is also is invalid Unicode text (and valid UTF-8), and reversible again by the same function.
 * So "mw.ustring.reverse" is also a "Unicode-conforming process", which does NOT require combining sequences to be complete after a leading base character, and does NOT require any normalization order, and does NOT require that grapheme clusters (valid only for specific locales) to be left untouched (combining sequences boundaries, or grapheme cluster boundaries for specific locales NEVER matter at all for strict Unicode process conformance, and not even for strict HTML conformance, or strict XML conformance).
 * Strict conformance of "mw.ustring.reverse" for its use with identifiers (or other technical syntaxes or linguistic orthographies) is not warantied, but this is true as well if you use "string.reverse", for exactly the same reasons.
 * "mw.ustring.reverse" will not preserve the grapheme locale-specific cluster boundaries, needed for correct collation or sorting, but this is true as well if if you use "string.reverse", for exactly the same reasons (linguistic and their orthographic considerations do not matter here).
 * Alternatively in the 2nd operation, you may prefer using the pattern matching:
 * '[\194-\244][\128-\191]+' (which detects only invalid original UTF-8 sequences which were reversed by the 1st operation and became possibly VALID) to restore their initial order. Here also the two successive operations may be made in any order (this does not change the result). This alternate variant for implementing "mw.ustring.reverse" in fact produces exactly the same result as the first variant.
 * you may want to replace the subpattern '[\128-\191]+' (in either of the two previous patterns, where it is used just beside the subpattern matching a valid leading byte), which greedily matches an unlimited number of continuation bytes (beside the leading byte), by '[\128-\191][\128-\191]?[\128-\191]?', which greedily matches at most 3 continuation bytes (beside the leading byte), because valid UTF-8 sequences cannot be longer than 4 bytes, in order to get some minor speedup (visible only with arbitrarily long invalid UTF-8 input that contains some very large chunks of invalid UTF-8 sequences made of very long sequences of continuation bytes, causing the "gsub" operation to find longer matches and to allocate longer substrings to be replaced by new reversed strings also very long). This changes the result of "mw.ustring.reverse" ONLY in invalid text, but the result is identical for valid UTF-8 input text, and the "mw.ustring.reverse" function still remains self-reversible. As well this variant will also remain a "Unicode-conforming process".
 * So I see absolutely no justified reason to forbid "mw.ustring.reverse" in Scribunto for MediaWiki, or Lua in general (outside MediaWiki), where it helps solving more complex text-handling problems, just like what "string.reverse" does for legacy texts encoded with 7-bit or 8-bit charsets (most of them technical, or restricted to basic English, and encoded with pure ASCII or ISO 8859 or similar very limited repertoires).
 * Asian users may want a function similar to "mw.ustring.reverse", but working this time on their legacy multibyte charsets (SJIS, GBK, GB18030...) to preserve the boundaries of valid multibyte sequences, like those used by UTF-8 (this is probably not needed for most installations of Mediawiki that just need UTF-8).
 * You may want to define a similar function working now with UTF-7, or BOCU-8 (most probably not needed in Mediawiki to render HTML pages on the web).
 * This won't work however with multibyte charsets whose encoding depends on the effective encoding state produced when encoding previous characters, notably ISO 2022 or encoding for old terminal or printer protocols like VT100/ANSI/etc. (with escape sequences to switch to another encoding, or with shift-ins/shift-outs or data link escapes to switch some parts of their encoding space across several codepages) or encodings using some stateful compression schemes: these charsets are not safely reversible (meaning that you must preserve texts at least from their begining, and cannot extract subtexts safely at most other start positions, and that if you reverse them, you need to preserve them at least from the end). These legacy charsets are now obsoleting rapidly; even compression is much better performed, in a simpler way without having to handle them in Mediawiki, by in the HTTP(S) transport layer (implemented by the webserver) and MediaWiki just needs to generate plain UTF-8 text.
 * In fact the whole standard "string" package should be disabled completely in Scribunto (including basic functions, notably length, substrings, and all search/match/substitution functions), and replaced by "mw.ustring" for everything: we must ensure that valid UTF-8 text will NEVER be broken and transformed into INVALID text, generating invalid HTML, or invalid XML, or inavlid JSON, and so on. Verdy p (talk) 19:53, 25 October 2018 (UTC)

This discussion was answered five years ago, and again three years ago. Continuing to write multi-kilobyte error-ridden screeds years after the fact is just disruptive. Anomie (talk) 13:28, 26 October 2018 (UTC)


 * The discussion above is closed. Please do not modify it. No further edits should be made to this discussion.

Example for string.format?
I read the description for string.format about 10 times, but I still don't really understand what it does. Would some kind person be willing to point me to an example or two? I have a feeling that it would be very useful in my coding, but I can't really grasp what it's used for at the moment. — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 12:05, 20 June 2013 (UTC)


 * Here is an extract of use the format function in my module to display coordinates and convert the angle value to text representation with specific accuracy, where  is a table with °, ', and " characters:


 * The roots of that interface come from the old printf from C language. In the example i.e. "%04.1f" prints float value passed with one digit after decimal point using 4 characters and padding with leading 0 if necessary. Paweł Ziemian (talk) 13:41, 20 June 2013 (UTC)


 * All this is heavily based on the C function printf. It's basically a way to concatenate strings and variables, applying formatting to the variables' values, in a way that can be more convenient than using the concatenation operator and individual functions to do the formatting operations.
 * The basic idea is that in a call like, the "%s" will be replaced by the value of the string variable 'var'. "%d" (or "%i") works the same for integers. "%o" will format an integer in octal and "%x" in hexadecimal, e.g.   results in "52 2a". "%e" will output a number in E notation, "%f" will format a number as a decimal with a fixed number of decimal places, and "%g" tries to be smart about choosing E notation versus decimal notation and trims trailing zeros in the decimal representation. For example,   results in "4.250000e+01 42.500000 42.5". "%c" takes an integer and outputs the corresponding character (as with  ). And "%%" is the escape in case you need a literal "%" character in your output.
 * Then there are the flags, width, and precision specifiers, which go between the "%" and the conversion specifier character. For example, using the width specifier as in "%10s" is like "%s", but it will pad with spaces on the left if the string is less than 10 bytes. If you add the '-' flag, as in "%-10s", it will pad on the right instead. "%10d" and "%-10d" work similarly; for the numeric conversions, you can also use the 0 flag (e.g. "%010d") to pad with zeros on the left instead of spaces. Precision truncates strings and specifies the number of digits after the decimal for "%f" and the like: "%.10s" will cut off the input string at 10 bytes, and "%.3f" will round to thousandths.
 * Lua leaves out a lot of the more complicated features in C's printf, though; the statements in the Scribunto Reference manual about things unsupported are for the benefit of people familiar with that so they can know what isn't available. And yes, someday I should probably make mw.ustring.format handle %s and %c using Unicode characters rather than bytes. Hope this helps. Anomie (talk) 13:59, 20 June 2013 (UTC)
 * Thank you Anomie and Paweł! Those explanations are both really helpful. As I suspected, this function looks really useful, and I will try it out right now. :) — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 01:44, 22 June 2013 (UTC)

Getting an Error with Italics
I am running a freebsd box and installed the latest lua port. I have been trying to get some of the wiki templates to work (specifically the SCOTUS) I keep getting "Script Error" all over the page. when I click on the link I get the following:

Lua error in Module:Citation/CS1 at line 186: attempt to index field 'text' (a nil value).

Backtrace:

(tail call): ? Module:Citation/CS1:186: in function "internallinkid" Module:Citation/CS1:591: in function "buildidlist" Module:Citation/CS1:1318: in function "buildidlist" (tail call): ? mw.lua:463: ? (tail call): ? [C]: in function "xpcall" MWServer.lua:73: in function "handleCall" MWServer.lua:266: in function "dispatch" MWServer.lua:33: in function "execute" mw_main.lua:7: in main chunk [C]: ?

If anyone can give me a clue as to what the problem might be. I tried removing and intalling the latest Parser and that didn't work either. It seems like it keeps throwing NIL or null values and I'm not sure why? Help!!!!


 * Hi there. It sounds like your version of Scribunto doesn't have the  library enabled. Try downloading the latest development version rather than the latest stable version, and see if that fixes your problem. Best — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 21:51, 2 July 2013 (UTC)


 * Thanks, I'll do that this afternoon when I get a chance. I'm currently running version 1.21 but I noticed that when I was looking at the snapshots there is a master development version as well....I'll use that one and see what happens.
 * Ok that seems to have solved the script error issue, but now the formatting is all messed up, do I need to download a new css file for this? [UPDATE] I deleted the CSS file and reloaded the copy from mediawiki and that made no difference. The formatting is all messed up now.
 * When you say that the formatting is all messed up, what do you mean? You'll need to give a bit more detailed description than that. Do you have an error message or a screenshot that you can give us? — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 09:04, 4 July 2013 (UTC)
 * I'm having a problem pasting a screen shot, here is a link to the page:

http://w[removeME]ww.i[RemoveMe]cce-t.n[RemoveMe]et/index.php/Roe_v._Wade I tried reloading the CSS file and that didn't make any difference, I'm just not sure what is screwed up now.
 * I guess nobody knows...
 * Still looking for some help with this one.
 * This doesn't look like a Scribunto problem. Instead, it is most likely that you are missing some necessary templates and/or modules. I think I managed to track the problem down to your wiki not having Template:Color - try uploading it and see if that makes things better. At any rate, things look much saner if you remove the "SCOTUS" parameter from the infobox in the page you linked. These kinds of problems are bound to crop up if you are relying on Wikipedia's templates, as they have been developed incrementally over 12 years and are, frankly, a big ol' mess. It's very easy to mess up a page because of missing dependencies, but then if you try and use all of Wikipedia's templates then things might start getting pretty slow. You'll have to experiment to find the best balance for you. — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 06:51, 15 July 2013 (UTC)

mw.title.compare
I have a quick question about  - what does it mean for a title to be less than, equal to, or greater than another title? Is it purely to do with the title length, or does it query the title text in some way? — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 09:07, 4 July 2013 (UTC)
 * When I invoke the lua code, it returns 0. It also returns 0 when I invoke  , so I don't understand me either. Automatik (talk) 10:39, 4 July 2013 (UTC)
 * compares two title objects, passing strings isn't going to work. It just compares the titles by,  , and  . You can see the Lua code behind it at . Anomie (talk) 13:00, 5 July 2013 (UTC)
 * Thanks you so much, I understand now. Automatik (talk) 01:19, 8 July 2013 (UTC)
 * The "mw.title" libary has another bug: it is not idempotent when it returns page instances that are exactly the same page.
 * For example when starting from a valid title object, reading the talkpage property, and from it getting the subjectpage property, we get a new title object that is NOT the same object, even if it compares equal.
 * This has a very bad effect: this generate infinite loops when traversing the content of objects because we cannot know that we have already visited an object (it is not possible to check that by comparing them with equality because not all objects are comparable this way, notably when traversing polymorphic data structures).
 * Clearly, "mw.title" should maintain a cache of title instances that have already been returned instead of creating new ones: "mw.title.new" needs to implement a true caching factory instead of always creating a new distinct array! The index of this cache is the full title string (including interwikis, namespace, base page, subpages, query parameters, and fragment). The cache will be used then to store other expensive properties: page existence, ID, content length, file content properties or metadata... Non-costly properties (such as URL parsing) don't absolutely need to be cached in title instances, when the "mw.url" module can process full title strings.
 * Note that a new array for the same title is returned EVEN if its (expensive) ID property was already known, such as the current page ID:
 * unexpectedly displays "false" for the same title (even if it says that "t==u" is true and if t.ID and u.ID are also equal). Verdy p (talk) 20:15, 23 April 2015 (UTC)
 * This rant is entirely unrelated to the existing discussion in this section. Bug reports belong in Phabricator, but if you do please include a reason why anyone would want to be recursively traversing title objects in this way. Also note that a cache isn't quite so simple when it needs to avoid T67258. And it might well be considered a bug that two calls to mw.title.new return the same object rather than two objects referring to the same title, as much as you're considering it a bug that they don't. Anomie (talk) 22:30, 23 April 2015 (UTC)
 * Recursively traversing objects is being performed by various modules, some of them are for debugging purpose only (dumping the content of a variable), others are used in data transforms to generate structured data (e.g. in JSON or XML or HTML tables). So yes the non-idempotence is a problem (a bug in mw.title module IMHO, and this is not "rambling" but something that cause these modules to enter in infinite recursion loops, using lots of memory and finally failing without any useful output except a server-side error). Verdy p (talk) 23:40, 26 April 2015 (UTC)

Text library
mw.text library is unicode safe ? it say that add functions missing from mw.string that it's not unicode safe.--Moroboshi (talk) 09:10, 6 July 2013 (UTC)
 * Fixed. Anomie (talk) 13:45, 8 July 2013 (UTC)
 * Thanks! --Moroboshi (talk) 06:00, 9 July 2013 (UTC)

mw.site.namespaces
Hi,

Does anyone know what's the defaultContentModel which is in the mw.site.namespaces table? Thanks by advance, Automatik (talk) 01:36, 8 July 2013 (UTC)
 * With ContentHandler, each namespace has a default content model; often this is "wikitext", but this can be changed. For example, on wikidata.org the default content model for the main namespace is "wikibase-item". Anomie (talk) 13:47, 8 July 2013 (UTC)
 * Thank you. Automatik (talk) 18:13, 8 July 2013 (UTC)

check if a page exist on another project
I'm trying to use  to check if a page on project different from the project where i run the lua code exist. But i get a  on every page I try even if the page exist. Is possible to check the existence of a page from a project to another ?--Moroboshi (talk) 21:13, 18 July 2013 (UTC)
 * No, this is not possible. Anomie (talk) 13:23, 19 July 2013 (UTC)

Format text/plain is not supported
Hi,

I've try to import a XML file from wikipedia.org. At the end of the import, I obtain this error relevant to Scribunto :
 * Échec de l'importation : Format text/plain is not supported for content model Scribunto

Do you have any idea of its origin ? --Fractaliste (talk) 13:21, 23 August 2013 (UTC)
 * Chances are you are using an old version of Scribunto on your local wiki, see bug 51504 for discussion of a similar issue, and bug 45750 for the more general issue. Anomie (talk) 13:16, 26 August 2013 (UTC)


 * I use the last version of Scribunto. But I make it work with manualy changing text/plain with "CONTENT_FORMAT_TEXT"

--Fractaliste (talk) 12:24, 2 September 2013 (UTC)

Could you explain to me how you manually edited text/plain?

--Jurugo (talk) 14:30, 28 October 2013 (UTC)

frame:expandTemplate
seems not to work properly. While  works as expected,   doesn't, calling someTemplate without passing it any parametres. —The preceding unsigned comment was added by 178.72.109.160 (talk • contribs) 00:50, 22 September 2013 (UTC)
 * I just tried it at the English Wikipedia and it worked fine for me. Can you give us any details about your specific situation? — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 11:05, 23 September 2013 (UTC)
 * Note that if  was loaded by , this will be fixed by 84985. Anomie (talk) 13:31, 23 September 2013 (UTC)

Title object question
If we get a title object using, and then get the talk page title object using  , is the expensive function count incremented? It seems like it would be, but this is not obvious from the manual. And is this also true for basePageTitle, rootPageTitle, etc.? It would be good to know this to know which methods I should be calling with pcall. Thanks. :) — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 10:59, 23 September 2013 (UTC)
 * All of these create a new mw.title object, so yes. As noted in the manual, these are equivalent to calling  with the appropriate parameters, and makeTitle increments the expensive function count. Anomie (talk) 13:34, 23 September 2013 (UTC)
 * It's a bit late, but I've added "this is expensive" to the relevant title methods and properties. I know this is redundant to the notice in the makeTitle documentation, but I thought that it was probably better to be clear than to avoid redundancy. — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 04:31, 22 October 2013 (UTC)

mw.text.trim error
Hello. I'm trying to install some modules from WP on my personal wiki using scribunto extension. Most of them fail mainly because mw.text.trim returns an error "attempt to index field 'text' (a nil value).". I get this for example in the debug console if I type =mw.text.trim(' some string ') Is her any explanation why it fails ? Phcalle (talk) 12:15, 27 September 2013 (UTC)
 * You are using too old of a version of the Scribunto extension. In particular, the version marked as being for MediaWiki 1.21 is too old. See Extension talk:Scribunto for a history of other people discussing this same question. Anomie (talk) 13:56, 27 September 2013 (UTC)

Control structures "for"
have a default value then the line

probably should become:

Rical (talk) 15:40, 16 October 2013 (UTC)
 * The problem is that  and   both raise an error. The step value must be omitted entirely or given a numeric value, so it's not a real "default" value. Anomie (talk) 13:14, 17 October 2013 (UTC)
 * Enforce the value 1 in these cases could be misunderstood and disturbing for users. Keep the errors seems a good way to help the user to write a better code. Then we could write "A step value false or nil raise an error, else the default value is 1.". --Rical (talk) 18:05, 17 October 2013 (UTC)

«But if exp3 is nil, the for doesn't work.» : In this case, can we "break" the for and continue after end to solve this strange case without error ? "A nil value do nothing" seems normal. --Rical (talk) 02:05, 26 January 2014 (UTC)
 * We are not going to rewrite Lua's handling of for loops, if that's what you're asking. Anomie (talk) 15:36, 27 January 2014 (UTC)

Scope of variable example
The code example for "Function declarations" is not clear. Somehow it leaves out simple function naming, and introduces mw.log out of the blue. If it wants to illustrate a scope, there only should be some nesting right? I know about scope, but this example does not explain to me what it is in Lua. -DePiep (talk) 10:23, 18 November 2013 (UTC)
 * Do you have a suggestion on what to replace it with? Anomie (talk) 14:18, 18 November 2013 (UTC)

Insertion of excessive detail in Language module documentation
@‎Verdy p: Seriously, I doubt most Scribunto users care at all about the minutia of IETF language tags, BCP47, and how MediaWiki's language codes aren't exactly the same thing. And we certainly don't need big warnings all over the place to "warn" people that they aren't the same thing. Please don't revert again. If you have suggestions for actual improvement to the existing documentation beyond what I already incorporated from your original edit, please propose them here so we can discuss it. Thanks. Anomie (talk) 14:14, 18 November 2013 (UTC)


 * This is a reference. One would assume that it contains information that all users care about.
 * It certainly should be mentioned that “language code” here is not what one would assume. A standard language code is usable in HTML  attributes, while the non-standard strings returned by the Language Library can invalidate HTML.
 * A reasonable user who knows what “language code” means in the rest of the world would not bother following a link to “Language codes are described at Language code.” There should definitely be a warning evident in this reference that reasonable assumptions are incorrect. —Michael Z. 2013-11-18 16:35 z 


 * I don't understand the revert (my edits add been accepted previously by others than you, Anomie), these were absolutely not complains or excessive details of what these functions do or why these codes are not valid BCP47 codes which are required by the HTML standard. We still need a way to provide correct BCP47 codes even if Mediawiki (in fact Wikimedia sites) uses specific codes (in fact they are subdomain names for projects, not really language codes, but these codes have slipped into ther projects that use them now incorrectly; for example you can see "simple" being used in OpenStreetmap tags such as "name:simple=*" only because they have been borrowed from Wikipedia or now Wikidata using these bogous codes which are strictly internal to Wikimedia projects).
 * These codes should have never been in MediaWiki itself, and all should be done to deprecate them fast (this should also concern the translations of Mediawiki on translate.net). This legacy inheritence from Wikimedia projects includes also correctly explaining why the Language library does not validate these codes and why there are 4 functions but still none of them are able to support standard language codes; these functions also have differences that are NOT explained in the doc: my addition added these for reference. We still have a missing function for validating BCP47 codes (but only in PHP, not in the Scribunto Lua module).
 * These are not details. Conformance to standards is a legitimate goal that users assume, even in Wikimedia sites, but more importantly when other sites will use MediaWiki.
 * May be you don't care about this, Anomie, but many users, even the beginners, need to understand what these functions do, and also more importantly what they don't and what are their differences.
 * Verdy p (talk) 23:30, 18 November 2013 (UTC)
 * You appear to still be under the misapprehension that these functions are supposed to be dealing with IETF language codes. They're not. This is made clear in the documentation. There is no need to further belabor the point, just like we don't need big warnings on every screwdriver to say "This is not a hammer!". Anomie (talk) 14:07, 19 November 2013 (UTC)
 * Except that in this case this is neither a screwdriver or a hammer. This is something else (undocumented).
 * Lack of documentation is a problem. But ONLY you consider this is details (other people were grantful and thanked me for exhibiting these differences). You continue to use and propagate a bad culture of unexplained assumptions, of keeping things secret or undocumented, or of assuming that people have the same interests as you. In fact most of your work in this documentation is just crap, and adding or perpetuating confusion. All is done here to ensure that you'll play the role of a God for this module, when Wikimedia wants more collaboration (every is replaceable, including you).
 * Consider getting yourself outside this documentation that you don't want to maintain (or are too lazy to update) when there are other people that want to develop it in a better way. You've made many people loose lot of time because of your bad work or blind reverts by rejecting all updates to this documentation, even if they were justified.
 * If you don't retire here, Wikimedians will create another better documentation elsewhere (in Meta, or Commons, or English Wikipedia, or Wikibooks) and will stop referencing this crap page that you have severely impacted with lies and bas assumptions everywhere, and that you refuse to correct and for which you don't want anyone else to contribute. Verdy p (talk) 19:44, 23 April 2015 (UTC)
 * What, specifically, do you think is actually missing from the documentation? Everything here that's actually relevant rather than a personal attack is already in the documentation, just not in the extremely verbose style you personally think is needed.
 * If you continue the personal attacks and other trolling, you may be blocked from editing this wiki. Anomie (talk) 22:34, 23 April 2015 (UTC)
 * You are still refusing to recognize bugs where they are, and missing documentation when it is important, and by ignoring the loss of time by module developers that experiment unexpected errors. This is not a personal attack but a general remark about this page that is not intended to cover only your own view but intended to be used by all Wikimedians.
 * All current limitations and bugs have to be listed, even if they may be solved later, and there should be a way to know if these will be solved or left as is (in which case we'll use something else because we know that there will be no maintenance). These considerations are for general audience, but you only see your own immediate interest. Verdy p (talk) 23:45, 26 April 2015 (UTC)

frame.args
How can I check if frame.args is empty, since next (frame.args) is always nil? —The preceding unsigned comment was added by Alex Mashin (talk • contribs) 15:59, 2 January 2014 (UTC)
 * Chances are you don't actually need to do this, just check for the args you care about. But if you really do need it, try something like this:

Thank you, your code worked. Alex Mashin (talk) 14:48, 2 February 2014 (UTC)
 * Doing this will cause all the args (if any were passed) to be parsed, even if you're not going to use them otherwise. Anomie (talk) 14:37, 3 January 2014 (UTC)
 * Yes, I need to do this: I create Lua functions with dynamic (i.e. unpredictable) parametres often; and in this particular case, I wanted my Lua function to take all parametres from encapsulating template call when the function is invoked without arguments.

getContent returns the unparsed content, but how to return the interpreted one?
I've just wrote b:fr:Module:Version imprimable to create the printable versions of all Wikibooks by a single line. However the books pages are full of templates and they aren't displayed, eg: Programmation_XML/Version_imprimable.

b:pt:Módulo:Book seems to do it but I don't understand the trick for that please? JackPotte (talk) 12:19, 3 February 2014 (UTC)
 * Hi ! On b:pt:Módulo:Book the trick is in the line . I'm treating the page as if it was a template, and "transcluding" it in the printable version. Helder 12:31, 3 February 2014 (UTC)
 * Thank you, I'm going to try to call the pages as templates (even if they aren't in their namespace). JackPotte (talk) 12:37, 3 February 2014 (UTC)

frame:preprocess
On it.wiki there is a lua function that used mw.message:text method, now I switched to use frame:preprocess. I would like to known frame:preprocess has the same potential problem of mw.message:text and could be removed in the future.--Moroboshi (talk) 11:39, 19 February 2014 (UTC)
 * frame:preprocess is good. The problem with the mw.message methods was that MediaWiki's MessageCache class makes it's own instance of the parser and processes 'text', 'parse', and so on using that separate instance. So any categories, links, and such coming from the message were recorded on that separate parser instance and not on the parser instance that is being used to parse the actual page. frame:preprocess, on the other hand, uses the same parser instance that is being used to parse the page and therefore all the categories, links, and so on get recorded in the right place. Anomie (talk) 13:55, 19 February 2014 (UTC)
 * thanks for the explanation.--Moroboshi (talk) 12:34, 20 February 2014 (UTC)

getContentLanguage
On Wikimedia Commons the whole interface translates, if the user sets a language code in his/her preferences. However wgPageContentLanguage will always be 'en', so within the scope of commons it would be very useful to determine the language a user has set in prefs, to translate lua module output accordingly. getContentLanguage does not seem useful to do this as it just returns the default content language of the wiki, not the users. How do we read the language actually used by the user? This would be the one to care about if a Module should translate its messages, or am I mistaken something fundamentally here? mw.message seems to only fit system messages and cannot advance to include module owned translation tables as I get it. Thanks for comments, recommendations. --Cmuelle8 (talk) 03:47, 10 March 2014 (UTC)
 * I've found some code in Module:Languages on commons, but I doubt this should do in the long run, should it? I have not tried it, but it looks ugly, since a normal template is preprocessed - just to get the users language..


 * The problem here is that Lua == content language, because it is server side and generates content. The trick above also really shouldn't be used. Content gets cached, and the above trick would mean a german user could get chinese content. For now, commons will have to remain using Javascript. TheDJ (talk) 11:37, 10 March 2014 (UTC)
 * Yes, the "int:lang" thing Commons uses all over the place is a bit of a hack, and it's not going to be supported in Scribunto other than by using the hack as above. I haven't actually tested it, but using int: via frame:preprocess shouldn't be any worse than using it in wikitext (i.e. it should fragment the cache based on user language, but shouldn't cause issues like bug 14404). Anomie (talk) 14:31, 10 March 2014 (UTC)

Tabel description
About the table definition (mw:Extension:Scribunto/Lua_reference_manual). The example code now has

I understand that it is not essential that the key and value are alike. Also accepted are: This is to improve (my understanding of) the documentation. -DePiep (talk) 18:54, 6 April 2014 (UTC)
 * Just now I had to try 2n tests to relearn how numbers can and cannot be defined in a table. Great. -DePiep (talk) 20:26, 12 June 2014 (UTC)

Examples
Sigh. I count 239 functions and not a single example. What am I supposed to know beforehand? Is there a secret class to follow? -DePiep (talk) 10:01, 7 April 2014 (UTC)
 * This is a reference manual, not a textbook. While a textbook would be an excellent idea, this shouldn't be it. Anomie (talk) 13:26, 7 April 2014 (UTC)
 * Use links. New to internet? (Or conversely you should remove the unwanted example here)
 * At least, I expected helpful links. -DePiep (talk) 05:49, 8 April 2014 (UTC) anger management & direction -DePiep (talk) 10:06, 8 April 2014 (UTC)

How to use "next" ?
It is not so easy to understand how to use. I used it in a local table with keys [1] and ["1"]. Could you add the right use : "for k, v in next, table" ? --Rical (talk) 09:10, 14 April 2014 (UTC)
 * In a for loop, you'd probably want to use "for k, v in pairs( table )" instead of trying to use 'next' directly.
 * To use next, you call it the first time as "k = next( table, nil )" (or just "k = next( table )") and then subsequent times as "k = next( table, k )". When the returned key is nil, you've reached the end of the table. Anomie (talk) 13:26, 14 April 2014 (UTC)
 * If we use an  loop, then a   loop, we must duplicate all the process inside with only a very small difference difficult to locate and to maintain. If we use   we write only once the process and the small difference become explicit and easy to maintain.
 * The fonction  exists and is usefull in some cases, anywhere, not necessary for read arguments. Like all others, it deserves a full description. --Rical (talk) 00:13, 15 April 2014 (UTC)
 * Functionality-wise and absent a __pairs metamethod, there is no difference between  and  . So I'm not following what you're trying to get at here. Anomie (talk) 13:22, 15 April 2014 (UTC)

Using a pattern capture
See Extension:Scribunto/Lua_reference_manual. Captures does not describe how to reuse a numbered capture (try  or  ?). -DePiep (talk) 17:01, 13 April 2014 (UTC)
 * What, like ? This is described slightly earlier in the document under "Pattern items": ", for n between 1 and 9; such item matches a substring equal to the n-th captured string (see below)". Anomie (talk) 13:23, 14 April 2014 (UTC)
 * So my statement is confirmed, thank you. Now how can we improve the documentation? -DePiep (talk) 19:15, 17 April 2014 (UTC)
 * Great. So you say: to understand the documentation, read its talkpage. That is where the links are! -DePiep (talk) 20:35, 12 June 2014 (UTC)

Lua error: too many language codes requested.
According to the documentation Lua calls are preferable to callParserFunction calls. So I was trying to replace with Both work just fine for individual examples, but I run into "Lua error: too many language codes requested." on my c:Module talk:Date/sandbox/testcases test page. Any way to avoid that error, other than not using formatDate? --Jarekt (talk) 15:53, 16 June 2014 (UTC)
 * Split the page up so it doesn't try to use more than 20 language codes per page. Anomie (talk) 13:04, 17 June 2014 (UTC)

work with media files
I am wondering if it is possible to work with media files using Lua.

My situation: I have the URL to a video, that I can get to look nice using wikitext via Lua:

But I do not want to have an embedded player, I want to show the respective thumbnail and define my own link target. Unfortunately I am not aware of how I can access this thumbnail.

For a quick-n-dirty solution I tried to use  in order to extract the image path with string magic, but preprocess does not process such a file expression.

How can I get the path of the thumbail of a video? Is there a Lua library I am not aware of that handles media files? Any other ideas how to do that?

Greetings --Sebschlicht (talk) 16:53, 16 July 2014 (UTC)
 * It's currently not possible to do that. Jackmcbarn (talk) 03:22, 17 July 2014 (UTC)

Frame object in called modules
I am trying to make a function in Wikidata that would retrieve the source of a claim and show it in the references. But the function is not called directly from the frame, and the caller function does not send the frame as an argument either. A I right, that there is no way I can use "ref" tags then ? --Zolo (talk) 12:33, 28 August 2014 (UTC)
 * If you don't want to pass the frame through as an argument to the function, you can just get the current frame by using mw.getCurrentFrame. Mr. Stradivarius on tour (talk) 14:18, 28 August 2014 (UTC)
 * Thanks ! I had somehow missed that :)/ -Zolo (talk) 20:51, 28 August 2014 (UTC)

Fullwidth hex digits: defined by Unicode
About Ustring_patterns. For the set  it now says: %x: adds fullwidth character versions of the hex digits.

This is correct, but it can be described more normative and Unicode-based (as the other bullets in that section are). See en:Unicode_character_property. Clearly, there are two Character Properties to be used:
 * : all ASCII hex digits (A-F, a-f, 0-9; 22 total)
 * : all ASCII hex digits plus all fullwidth hex digits (22 + 22)

Describing the  set using these Properties is basing it on a sound Unicode definition. Outside of this documentation change, there are no material effects as far as I can see. -DePiep (talk) 19:17, 17 September 2014 (UTC)

Something is broken in mw.string module
There is some problem with Lua pattern matching in pl wiki:

There is expected that both calls returns error with match not found, which is true here, but fails in pl wiki (LuaSandbox 2.0-7; Lua 5.1.5). The problem can be observed here. Unfortunately the first match returns incorrect value "4". Paweł Ziemian (talk) 17:40, 9 October 2014 (UTC)
 * I checked other few wikis (en, de, ru, test, test2) and there is older version of Lua (LuaSandbox 1.9-1; Lua 5.1.4). Is this version upgrade in pl wiki intentional? Paweł Ziemian (talk) 18:02, 9 October 2014 (UTC)
 * It appears that there's a bug in HHVM and PCRE; see some discussion at around 01:30 in this IRC log. I don't know whether the bug has been filed anywhere yet.
 * As for the differing versions of LuaSandbox, apparently the 2.0 version was only compiled and installed for HHVM and not Zend for some reason. If you have the HHVM beta feature enabled on a wiki you'll see 2.0, otherwise 1.9. Anomie (talk) 13:15, 10 October 2014 (UTC)
 * Thanks for explanation. Today I see both results correct. Paweł Ziemian (talk) 17:57, 10 October 2014 (UTC)

mw.text.split
It would be nice if this returned also the count of splits eg.
 * value, count = mw.text.split(str, " ")

Otherwise a second line is needed to get count eg.
 * novalue, count = mw.ustring.gsub(str, "%S+", "")

Typically functions return the number of times they performed an action. -- 71.114.106.88 23:57, 12 October 2014 (UTC)
 * Did you try get number of elements in the returned table? I think there is relation between them, that is (number of splits) + 1 = (number or items). Paweł Ziemian (talk) 15:08, 13 October 2014 (UTC)

Additional libraries
How can I get (install) additional libraries in Scribunto, like this one: isbn? Jaider msg 22:37, 1 December 2014 (UTC)
 * If they are pure Lua libraries, then you may be able to add them as modules in your wiki's module namespace, with some caveats: they must work under Lua 5.1, and if they use any of the standard Lua functions that have been changed or removed in Scribunto, they may need to be altered. Some pure-Lua libraries may not be able to work at all due to the differences from standard Lua. If that doesn't work, then you need to add them to Scribunto as Scribunto libraries. This isn't intended as a process for end users to follow - you would need to do the coding yourself, and either submit a patch here or maintain a private Scribunto repository. — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 07:16, 12 December 2014 (UTC)
 * Thank you @Mr. Stradivarius. I was able to add the ISBN library by putting the lua files as modules in the wiki's module namespace. It works great! Again, Thank you. Jaider msg 21:41, 17 December 2014 (UTC)

Expensive properties and methods in title objects
At the moment the properties/methods in #Title objects that return a new title object are marked as "this is expensive". This will need to be changed now that 178698 was merged, but I'm not sure what exactly it needs to be replaced with. I can see that the properties "id", "exists", "isRedirect" and "contentModel" need to be marked as expensive, but how about the methods, e.g. "getContent"? Do any of them increment the expensive function count as well? — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 06:51, 12 December 2014 (UTC)
 * The methods that return a new title are fixed now. I mentioned those 4 properties in the prose, since they work a little differently than the other expensive properties. No additional methods count as expensive. Jackmcbarn (talk) 16:18, 12 December 2014 (UTC)
 * Thanks for that. About the other expensive properties - do they depend on the expensive data being fetched, or are they separate? In other words, say someone writes the code  and the "Foo" page hasn't been loaded previously. When protectionLevels is accessed, is the expensive function count incremented by one, for just the protectionLevels access, or is it incremented by two, for the normal expensive data and for the protectionLevels access? — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 08:57, 13 December 2014 (UTC)
 * Actually, ignore that - after I typed out that question I realised that I could test it myself. I see that for my example the expensive function count is only incremented by one, which is rather nice. I think we need a clearer way of indicating to people that exists etc. is expensive while still maintaining the distinction with protectionLevels. I'll have a go at doing that now. — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 09:33, 13 December 2014 (UTC)
 * Ok, docs are now updated. — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 15:35, 14 December 2014 (UTC)

Splitting into subpages
The manual is now 172k in size, and it's slowly but surely getting bigger as more features are added to Scribunto. There may also be a couple of large jumps in size at some point relatively soon, as there are two new libraries in the works: getArgs and mw.math. I think it would make sense to split the manual up into subpages before it gets any bigger. For one thing, this would make the page a lot easier to read on mobile - splitting the page up would mean we could use more level two headings on the subpages, and level two headings get collapsed on mobile. At the moment, mobile users have to do a lot of scrolling to find the library that they want. I'm open to suggestions as to how to do this, but I'm thinking we should at least have a subpage for the Lua language, one for standard libraries, and one for mw libraries. — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 14:12, 14 December 2014 (UTC)
 * Good idea. I'd like to see all the MediaWiki-specific stuff kept here, and all the stuff copied from the official Lua reference manual moved to a subpage. Jackmcbarn (talk) 02:48, 16 December 2014 (UTC)
 * I like how it is currently organized. Often use Ctrl to find something I am sure Lua or one of its MediaWiki extensions has. -- Rillke (talk) 13:41, 16 December 2014 (UTC)
 * How about including a summary of what properties/methods are available on the main page, and having the main documentation on a subpage? — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 06:11, 18 December 2014 (UTC)


 * Or you might appreciate the recent German solution and its page source? w:de:Hilfe:Lua/* Developed the other way around. – Greetings --PerfektesChaos (talk) 22:56, 18 December 2014 (UTC)

mw.language.fetchLanguageName
I recently did an experiment with  where I gave it the code 'ara'. If one is to believe the documentation, the returned string should have been 'Arabic'. Instead, the returned string was 'ara'. When I gave  the code 'lad', the returned string was 'Ladino' which is the correct language name for that ISO639-3 code.

This behavior is inconsistent and contrary to the documentation. Similar results are obtained with, which see.

—Trappist the monk (talk) 14:54, 14 January 2015 (UTC)
 * When I try, I get the empty string rather than "ara". This is not contrary to the documentation:
 * Language codes are described at Language code. Many of MediaWiki's language codes are similar to IETF language tags, but not all MediaWiki language codes are valid IETF tags or vice versa.


 * IETF language tags do not include all ISO 639-3 codes (it uses ISO 639-1 codes where one exists, as 'ar' does for Arabic), and MediaWiki language codes do not include all IETF language tags. Anomie (talk) 14:42, 15 January 2015 (UTC)


 * Right, I misspoke; I did the test in en:Module:Citation/CS1/sandbox which returns the code if  doesn't return a language name.


 * Is there documentation someplace where the 'similarity' to IETF language tags is defined (and also dissimilarity)? If there is a standard (IETF), why not adopt the standard?  If there are reasons that the standard has not / will not / should not be adopted, shouldn't those reasons be clearly and unambiguously documented?


 * —Trappist the monk (talk) 17:02, 15 January 2015 (UTC)
 * Both of you are wrong. "IETF tags" are in fact BCP47 tags (those described in a list of RFC's and maintained in the IANA database). BCP47 are the actual standard used in W3C standards (including HTML, XML, SVG), also used in other languages (including SGML), and international databases (such as CLDR). BCP47 tags are not just language codes, they are locale codes. But not all language codes are valid locale codes in BCP47. For example ISO 639 contains many language codes that are NOT valid locale codes, and also forgets many codes that have been dropped even if they are still valid and used in BCP47.
 * In summary, don't look at ISO 639, it's not relevant at all (even ISO 639-1 only is irrelevant, it also contains codes that are invalid locale codes!). ISO 639 codes are NOT stable across time, they have lot of unsolved compatibility problems and have in fact never been developed to be used as locale codes: they are just codes developed for bibliographic purposes. Their "technical" use (introduced in ISO 639-2) has failed completely. The world uses BCP47 instead for localisation (and in fact many librarians, and even linguists, now use BCP47 locale tags instead of the old ISO 639, which is a dying standard with too many problems).
 * But also note that Wikimedia defines additional locale codes that are not standard in BCP47 or conflicting with it (e.g. "simple" or "als" or "nrm", or "map-bms", or "fiu-vro", or "sr-ec", or "sr-el") and that we should deprecate and even drop later, we don't need them (even if we keep their existing local mapping to wiki database names, and their mapping to public domain names for interwiki prefixes, because this is a completely different thing! Interwiki prefixes are NOT locale codes, and NOT language codes).
 * On the opposite, locale codes supported by MediaWiki are abusively named "languages" in . This library is just full of bugs and in fact a real piece of untested junk that confuses everything (and that even does not work the way it is currently documented and has severe limitations!). In Lua, stay away from the "mw.language" library, it has to be completely rewritten (it is even less functional than what it isued to be in the past, because of added limitations and bugs)! But in fact all these bugs and limitations are coming from the equivalent module in PHP (that has exactly the same bugs and that should be rewritten as well!) Verdy p (talk) 19:09, 23 April 2015 (UTC)

This documentation page is crap
Why is there a lua reference in there, like Lua's tokens and stuff? I want to know what's that frame variable do? How do I pass arguments (other than just what function to call) - it seems to almost all be Lua's standard library! — Preceding unsigned comment added by 137.205.238.124 (talk) 16:18, 12 March 2015 (UTC)
 * Because this is a reference to Lua as it exists in Scribunto, not just to Scribunto's extensions to Lua. The frame object is documented at Extension:Scribunto/Lua reference manual. Accessing arguments passed to the #invoke parser function is described at Extension:Scribunto/Lua reference manual. Anomie (talk) 14:07, 12 March 2015 (UTC)
 * Thanks for the response (not sure how to reply to) hope you get this - this certainly needs to be made more clear, and is far more important than "math.abs is included!" I think these ought to be two pages. One about Scribunto and wiki and another about the Scribunto environment. — Preceding unsigned comment added by 137.205.238.147 (talk) 20:14, 12 March 2015 (UTC)
 * You replied correctly, although do remember to end your post with " ~ " to display a signature. While this page is large, I'm not sure what the best division might be, particularly with the number of cross-references between what would be different pages. Anomie (talk) 13:14, 13 March 2015 (UTC)
 * I'm not alone to think that this Scributo doc page is crap. Notonly it mixex everything, it does not clearly differentiate what is standard Lua and what is not, and it does not even correctly document what is really working or not.
 * Clearly the MediaWiki-specific libraries should be in separate pages or subpages (and it needs lots of updates base most of the functions are simply incorrectly documented, and you Anomie, do not even want to have this documented).
 * In additions, some MediaWiki libraries have also specific behaviors in some wikis, and some wikis alos have their own Scribunto libaries not listed here !
 * In summary, this page should just link to the releval Lua.org documentation (we don't need to include it, but need to list the Lua versions we support in Scribunto). Then it should concentrate on describing only the "frame" objects (which are the only thing we need to interact with MediaWiki in Scribunto). All other libraries should be in separate pages (including "Ustring", "mw.language", "wm.title", libraries for wikibase clients, libraries to parse file contents, libraries to interact with user preferences, or user notifications, or liquidthreads, or for interacting with specific special pages and other mediawiki extensions, or just generic libraries in pure Lua...)
 * Verdy p (talk) 19:31, 23 April 2015 (UTC)

Rendering a gallery
I cannot make Scribunto to render a gallery from ca:Module:FotoNumero. I get "" in the wiki page instead. See ca:User:QuimGil/proves. I have tried mw.text.decode, mw.text.encode and mw.text.tag, but I still would get the tags instead of the gallery. Help, please.--QuimGil (talk) 13:27, 15 March 2015 (UTC)
 * See Extension:Scribunto/Lua_reference_manual. --Vriullop (talk) 15:41, 15 March 2015 (UTC)
 * Thank you! I had tried that as well, but a) didn't understand the documentation, and b) clearly my attempts were wrong because I kept getting error messages.--QuimGil (talk) 16:37, 15 March 2015 (UTC)

mw.ext.?
Where I can find some more information (documentation) about extensions available in  table? There is a list ["ext"] = { ["TitleBlacklist"] = { ["test"] = function }       ["FlaggedRevs"] = { ["getStabilitySettings"] = function }       ["ParserFunctions"] = { ["expr"] = function } } I am interested about the, which is used in en:Module:Location map. Paweł Ziemian (talk) 20:50, 6 April 2015 (UTC)
 * The developers of those extensions are supposed to have added links to their documentation from Extension:Scribunto/Lua reference manual, but it doesn't seem that any of those have. Anomie (talk) 13:18, 7 April 2015 (UTC)
 * I tried to find roots of the code and found that the only documentation of those are commit messages, when the modules were introduced: [//git.wikimedia.org/commitdiff/mediawiki%2Fextensions%2FParserFunctions.git/f7bd89e435ab5cfcc310d92f7ae7bb929cf14f24 ParserFunctions], [//git.wikimedia.org/commitdiff/mediawiki%2Fextensions%2FFlaggedRevs/7cff6c522c2af6b0ceb23b0574be056b134d2469 FlaggedRevs], [//git.wikimedia.org/commitdiff/mediawiki%2Fextensions%2FTitleBlacklist.git/bf188e7af1bccefba5662e80e635249b695e3e3f TitleBlacklist]. All of them are made by Jackmcbarn. It would be glad to know if i.e. ParserFunctions extension is stable and is ready to use for everyone, or it is still in experimental state and using it is not recommended yet. Paweł Ziemian (talk) 20:37, 8 April 2015 (UTC)
 * They're all stable and ready to use for everyone. Jackmcbarn (talk) 16:02, 12 April 2015 (UTC)
 * But they are not all deployed on the same wikis. For example on Commons we get

=mw.dumpObject(mw.ext) {  ["ParserFunctions"] = { ["expr"] = function#1, },  ["TitleBlacklist"] = { ["test"] = function#2, }, }
 * In some editions of Wikinews and Wiktionnary, there are a few other libraries. My opinion is that the Special:Version page should list these libraries and their description, in the section related to Scribunto (where Scribunto is installed of course).
 * Some extensions are also not preloaded in "mw.ext" but may be loaded on demand. We lack a way to see the list all external libraries (loaded or not), and where they are supposed to be bound to within Lua globals:
 * For example in Commons, "_G.package.loaded" currently has these keys:
 * '_G', 'debug', 'libraryUtil', 'math', 'os', 'package', 'string', 'table' — a subset of Lua 5.1 core libraries (some of them modified for Scribunto)
 * 'mw', 'mw.html', 'mw.language', 'mw.message', 'mw.site', 'mw.text', 'mw.title', 'mw.uri', 'mw.ustring' — MediaWiki core libraries (more restricted than its PHP library)
 * 'mw.ext.ParserFunctions', 'mw.ext.TitleBlacklist' — Mediawiki extension libraries (not documented on Scribunto)
 * 'mw.wikibase', 'mw.wikibase.entity' — additional Mediawiki extension libraries implementing the Wikibase client (for querying Wikidata).
 * The Scribunto doc page becomes indigest and should now be splitted with separate pages for each library.
 * One of these libraries has a special interest: 'mw.ext.ParserFunctions', it can be used because mw:frame methods do not permit expanding parserfunctions, they are only converted to stripped markers, and their evaluation is delayed).
 * But only one parser function is enabled, and it is the "#expr:" parser function, this allows computing values passed in parameters to Lua or computing expressions built dynamically (because Lua's standard method "load(string)" is not supported, using the syntax supported by #expr, without having to parse them in Lua (the existing implementation in PHP is faster, even if it has the same quirks): pass it a string, it returns a string like in MediaWiki  returns the string.
 * I'd like to have a fews existing other MediaWiki parser functions or extension tags mapped as well, and notably the "Special:Prefixindex" parser function (to avoid having to generate many "#ifexist:" from a list of language codes and exploding the limits, this would generate a list of subpages for a given base page) and the extension tag "#tag:categorytree" to get in a single query a list of 200 member pages by default in a category (or up to 500 like when viewing a catagory, with the adhoc option of this extension tag); that categorytree should also have an option to return the list in a simpler format, just page names separated by newlines, or returned as an array of page names, possibly also with the common prefix hidden with the option "hiddenprefix=1", and hidden redirects with the option "hideredirects=1", exactly like when viewing the special page that should support also the query option "format=text" to avoid generating HTML-formatted lists of anchor elements or wiki-formatted wikilists of wikilinks, or "format=json" to get this list just in the standard JSON format of the API). Instead of having a cost of 1 per #ifexist:, we would have a cost of 1 for the whole list of existing translations, generated in a single query to the database and we would be able to avoid testing the 400+ languages supported (and exploding the limits of costly individual "#ifexist:" parser functions or costly individual "mw.title" function calls, and with much better performance; an alternative would be to add "(mw.title):subpages" to get this list of subpages, or  with the same options as in Special:Prefixindex, or   also with the same options as when viewing category pages...  Verdy p (talk) 04:22, 20 April 2015 (UTC)
 * That's extremely long. Your understanding of strip markers is incorrect, they are not "delayed parsing" but rather hide already-generated raw HTML from further parsing (although post-parsing hooks could be used to postprocess). Feature requests belong in Phabricator. Anomie (talk) 13:49, 20 April 2015 (UTC)
 * You're completely wrong. These stripped markers are definitely NOT preparsed by extensions, and I can prove it, because I tested it (not like you): this is the essential thing that changed in last december and that has caused many templates or pages stopping to work.
 * I can affirm that these stripped templates are not preparsed, but only storing the name of the extension to use and the value of its parameters, and that everything is delayed; these extension will be called later, (and at least always after the execution of Lua). Visibly you have not tested these or do not know that this is something that changed in last December. Stripped markers (as they are seen in Lua) are just containing the parsed text, not its expansion (and not just because this expansion may contain pure HTML incompatible with the wiki syntax such as javascript or anchor elements with arbitrary URLs, but also because this execution of extension hooks takes time on the server even when such execution is not needed, because the Lua code will choose to not return them even if they were present in Lua call parameters).
 * As stripped markers are unique identifiers for each instance, their result can also be cached so that the same instance will be executed only once, even if the result is duplicated on the page.
 * Anyway I don't like your way of making blind reverses of everything in the documentation, because you (only you!) just want to keep things undocumented, even when they have changed or are severely limited, or when functions may return errors in certain conditions (just like those that I listed for the "mw:language" module, which were accurate).
 * May be you could think about better wordings for English (it's not my native language, but I make efforts, not like you...), but dropping everything is clearly unacceptable and a very selfish behavior. You have abused your privileged position when also adding personal threats in your reverts. Your staff membership does not authorize you to block someone that is honestly contributing, when you, instead, are just abusively deleting useful content (for clearly unjustified reasons). The acceptable behavior would have been to correct things or enhance them, instead of using your personal judgement about what you think is "wrong" but was in fact an effective reality.
 * This page is not supposed to document how Scribunto should idseally work, but how it currently works. Its limitations (or even bugs) have to be documented somewhere, because all Wikipedians want to understand why their code is no longer working or has never worked: they spend hours looking for unexplained problems, and you don't give any consideration to their problems and the time they invest in looking for solutions.
 * So replying "TLDR" is definitely not a good reply (it's just lazy from you), when such details are in fact essential. Verdy p (talk) 18:45, 23 April 2015 (UTC)
 * When I look at the actual source code, I see that it's obviously storing replacement text rather than "the name of the extension to use and the value of its parameters" as you claim. Anomie (talk) 22:43, 23 April 2015 (UTC)
 * If this was the case, that source code would call for the expansion of its parameters before doing the stripping. This is not the case, all parameters in the specified text are left "as is". They will be processed only when they will be unstripped (by the hook mechanism present in this source). So now extensions are just stripping parameters and delay their effective expansion (and notably those that generate plain HTML, including plain HTML anchors, or javascript, or some unsupported HTML elements such as "video", or unsupported HTML attributes such as "onload=", or that generate embedded CSS stylesheets in a HTML "style" element, or that would generate "frame", "iframe", "xml", "object", "input", "textarea", and similar elements forbidden in Wikitext... or even just "thead", "tbody", "tfoot", "colgroup", "col", "caption", or other semantic document structure elements of HTML5, even if they have no good reason for being restricted in Wikitext).
 * But thanks for the link I see now that there's a "unstripGeneral" function (not documented, again!), but I don't see it mapped in frame objects, it remains only in the internal PHP code and not accessible to Lua (or I have still not found how to access it).
 * Look for "extensionSubstitution" method used in the MediaWiki parser, that now supports so called "half-parsed" text, which is stripped for later expansion, by the hooks registered by extensions (not all extensions are still using this delayed expansion mechanism, but their number is increasing; for now only basic parser functions such as "lc:" and standard templates are being expanded immediately and don't need stripping, but other extensions — such as dated magic keywords, or version magic keywords, or magic keywords counting pages in categories, or enumerating their protection level, or even the standard wikitext generating wikilinks — are not expanded immediately, they are in "half-parsed" state for later processing, and they use their own caches if needed ; there's some complex "ghost" processing in the parser to allow pages to be processed faster, when their expensive immediate expansion is strictly not needed and may be avoided by conditional parser functions such as "#if:" or "#switch:"). The main advantage of this delayed expansion is that it allows a much faster construction of the DOM tree, with a smaller resource footprint in the server.
 * Now what I'm looking for is: how to use "unstripGeneral" in Lua, we only have "unstripNowiki", and "unstrip" that kill all other stripping markers with the "general" type (which is in fact all other extension tags not bound to a simple core parser function). Verdy p (talk) 23:53, 26 April 2015 (UTC)
 * You seem to be confusing strip markers with the optimization of not processing an argument to a template or parser function (including Scribunto's #invoke) until it's actually used. If something like were to be merged, then you'd be potentially correct. Or, as I said, something could be using various parser hooks to try to post-process things at some level, but I'm not aware of anything that actually does this in the manner you describe.
 * There is intentionally no way to access  from Scribunto, it was removed in  due to T63268 and T73167. Anomie (talk) 13:55, 27 April 2015 (UTC)
 * The only good reason given is in the second issue T73167 which says: "To prevent access to tokens, do not allow Scribunto modules to unstrip special page HTML." But the solution taken is extreme: only the tokens need to be protected. I don't see why all "general" stripped tokens have to be cleared. If there are security tokens, they should not be using te "general" type for their stripped text, but a "secure" type. For the first issue T63268, I have absolutely not seen why there was an issue (most probably the issue was just the second one creating the first one indirectly).
 * In fact I am convinced that most extension tags should not be processed immediately but should just be half-processed by just creating stripped markers only containing the extension tag and its parameters, to be processed later. It would make the parser much more efficient. But now as they will be stripped in a "general" stripped tag for most of them (except "secure" ones), using unstrip would not kill them and would allow their expansion.
 * If there are things hidden in the unstripped text that should not be revealed, they will be exposed later in the final web page, so all issues will exist as well by using a second scrpting server querying the same page: the issue remains usable from an external client (hiding tags only locally to Lua will not secure them). Verdy p (talk) 20:42, 27 April 2015 (UTC)

get template parameter's by order
i'm trying to extract from the template the names of the parameter by read them from the "templateData" using "mw.text.jsonDecode( s )". i am able to do it but when i'm using for...pairs, the parameter's names returns in diffrent order from "templateData". i tried to use the flag "mw.text.jsonDecode( s, mw.text.JSON_PRESERVE_KEYS )" but it still not help. what is worng?! Badidipedia (talk) 13:10, 17 May 2015 (UTC)
 * If the incoming JSON data is encoded as a JSON object, note that JSON objects are unordered so there isn't technically an order to be extracted in the first place. If the incoming JSON data is an array, use  instead of  . Anomie (talk) 13:53, 18 May 2015 (UTC)
 * Thank you, Anomie. as i saying, i was took the data from "Template:" pages and the text passed to the function  as string so i belive it's consider as serialzed and therefore - ordered.


 * I'm adding the code here. maby it will help to understand the problem:


 * Badidipedia (talk) 18:21, 18 May 2015 (UTC)
 * As I said, there you're accessing a JSON object which by definition has no order. Anomie (talk) 13:20, 19 May 2015 (UTC)
 * Thanks again Anomie. if i'm understand you correctly, by saying "JSON object", you are meaning to the function's return value (Table i guess, and this is explain whay it's unordered). It's mean that if i want to do it, i must learn JSON from start to top and write a lot of code. Wish me luck... (Sory abaut my terible english..) Badidipedia (talk) 18:13, 19 May 2015 (UTC)
 * See ru:Модуль:TemplateDataDoc. Jack who built the house (talk) 20:34, 24 June 2018 (UTC)

Function declaration and invocation parameters
Thanks for writing this useful manual; I stayed a Lua/Scribunto newbie for a while so now I can offer myself as guinea pig user of the documentation.

I was utterly confused by the lack of information on how to create a simple module which takes some (named) parameters and outputs a string: this seems to be a very common use case, yet it's not covered.

In detail: as a result, information in the sections about function invocation and declaration (which I did check, as they sounded like what I needed) was misleading, especially given the lack of a realistic example module. --Nemo 09:34, 11 July 2015 (UTC)
 * there is one such minimal example at Lua/Tutorial, which I initially skipped assuming the reference manual would be more complete;
 * then most information is hidden in the "Frame object" section, which I'm never going to check unless I already know what it says (i.e. that I must use it):
 * I'm not very fond of sticking that unexplained Scribunto-specific see-also in the middle of the documentation on how to declare a Lua function. But you're right in that the whole "frame object" deal isn't explained too well, so I added a section titled "Accessing parameters from wikitext" right at the top of the document. Feel free to improve it if necessary, although we should avoid turning it into a tutorial rather than a reference manual (and note that #frame.args already includes most of what Lua/Tutorial does). Anomie (talk) 13:24, 13 July 2015 (UTC)

Accessing protection levels
I'm using DPL to generate a list of pages I need to protect and came across something a little odd. If I use  to generate a title object, I add to the expensive function limit (perfectly understandable). However, I then need to check the protection level of said page, which is another expensive function. Are the protection levels not loaded as part of the initial  instance? mdowdell (talk) 19:47, 28 July 2015 (UTC)
 * No, because they take an extra database query to load. Anomie (talk) 13:09, 29 July 2015 (UTC)

Documentation for newline in long brackets
Extension:Scribunto/Lua reference manual says:
 * if an opening long bracket is immediately followed by a newline then the newline is not included in the string, but a newline just before the closing long bracket is kept.

and then gives as an example: Why is the newline in  between "baz" and "]]" omitted? DMacks (talk) 05:37, 9 October 2015 (UTC)
 * Because it was incorrect. Fixed. Anomie (talk) 13:14, 9 October 2015 (UTC)
 * Ah, that does explain the situation. Thanks:) DMacks (talk) 10:30, 12 October 2015 (UTC)

Find all references
Recently I faced the problem of finding all places where specific function from module is called via  from template. That was not trivial. The only thing I was able to receive is a list WhatLinksHere to the module, where the function is defined. But the list has many items that do not call the interested function instead any other available in the module. To resolve it I had to create separate module (BTW named Module:Name/deprecated) and copy all its code there. Then in the main module created new implementation, which redirects the call to separate module: The new implementation added log entry with parent frame title that help me getting template name that calls the function, when looking into the log generated in the article preview. When the template with reference was found, I was able to remove it or change to the new one. This removed relevant part of articles from the WhatLinksHere list. Finally I was able to fix all references. However, the whole process is not trivial, and very time consuming. Could it be simplified somehow? It could be useful if  could create "shadow" categories, which are emitted after the whole page is created, and are declared via some specific   api function. Generating categories independently from the returned value can be very powerful method for various diagnostic purposes. Paweł Ziemian (talk) 19:01, 22 October 2015 (UTC)
 * You could have skipped the "copy all its code there" bit and just added a  (or better,   since that doesn't even require that "Module:Name/deprecated" exist) to the original function. To request new features for Scribunto, such as a   function, please file a bug in the "MediaWiki-extensions-Scribunto" project requesting it. Anomie (talk) 14:15, 23 October 2015 (UTC)
 * Thanks. Paweł Ziemian (talk) 15:33, 23 October 2015 (UTC)

ustring pattern dont recognize char
Ustring pattern dont recognize old-slavic char 'І'. Visualy it like latin 'I' but has other code. All other simbols works fine. This returns 'q' but must 'І'. --Vladis13 (talk) 03:20, 10 November 2015 (UTC)
 * This sounds a lot like T73922, so I added details distilled from this case there. Anomie (talk) 14:53, 10 November 2015 (UTC)
 * Unfortunately, issue there year now and no solution in sight. Is way to bypass the bug? --Vladis13 (talk) 00:45, 11 November 2015 (UTC)

frame object in debug console?
Is there a way to create a frame object in the debug console? Or at least something that works like one.

Suppose I want to test a function that uses frame:preprocess, even mw.getCurrentFrame return nil, so I get an error.

Currently, I'm using something like this:

181.47.160.72 05:54, 13 November 2015 (UTC)
 * does not return nil in the debug console. Anomie (talk) 14:35, 13 November 2015 (UTC)

Stats of users groups
In site.stats and usersInGroup I found by some tests:
 * administrators = usersInGroup( "sysop" )
 * bots = usersInGroup( "bot" )
 * patrollers = usersInGroup( "patroller" )
 * bureaucrats = usersInGroup( "autoconfirmed" )
 * accountcreator = usersInGroup( "accountcreator" )
 * could you better complete all use cases?--Rical (talk) 21:03, 14 November 2015 (UTC)
 * Bureaucrats should be .   should give 0 since users aren't directly added to that group, it's dynamically added by MediaWiki when conditions are met.
 * As for finding group names, use API action=query&meta=siteinfo&siprop=usergroups (e.g. ) to get the group names, then see the messages "MediaWiki:group-{name}" (e.g. MediaWiki:group-sysop) to find the human-readable names. Or go to Special:ListUsers and use the "Group" dropdown, then look in the URL for the value of the "group=" parameter. Or go to Special:ListGroupRights and look at the value of the "group=" parameter in the "(list of members)" links. Anomie (talk) 14:15, 16 November 2015 (UTC)

Serial comma needed in listToText
Serial comma is proper basically everywhere.

en:Template:Further, en:Template:Further2, and en:Template:See also use  (via en:Module:Further and en:Module:See also).

They produce results like: Further information: a Further information: a and b Further information: a, b and c See also: a See also: a and b See also: a, b and c

The templates produce incorrect results because listToText produces incorrect results.

The results should be: Further information: a Further information: a and b Further information: a, b, and c See also: a See also: a and b See also: a, b, and c

The additional comma applies only for 3 or more items. The results for lists of 2 items must NOT be: Further information: a, and b See also: a, and b -A876 (talk) 08:56, 15 November 2015 (UTC)
 * Bug reports and feature requests should be filed in Phabricator. Anomie (talk) 14:19, 16 November 2015 (UTC)

Interpreter error signal 11
I tried to follow the example of the Bananas module on the project page, but I when try to create the Module:Bananas I get the message Script error: Lua error: Internal error: The interpreter has terminated with signal "11". But nowhere can I find an explanation of what signal 11 means. Why is the interpreter being invoked anyway, when all I'm trying to do is to create a new page? Eric Corbett (talk) 14:01, 17 November 2015 (UTC)

Is the problem simply that the binaries distributed with the 1.25 version of Scribunto don't work? In particular, I'm using the 64-bit Linux binary. Eric Corbett (talk) 19:07, 17 November 2015 (UTC)
 * This can be. The binaries are of course system dependent and a signal 11 (SEGFAULT) usually means execution is failing hard. They 'should' work in most cases, but it's no guarantee. There is some more info on binaries here. You can easily test if they work by using them directly for a hello world. And pages are validated before they are saved, so that is why you see this during page creation. —Th e DJ (Not WMF) (talk • contribs) 22:34, 17 November 2015 (UTC)

Analog of
How to make analog of, to assign "bar" only once for all identifiers? Without creating dublicate array-field for each parameter, like: --Vladis13 (talk) 09:54, 19 November 2015 (UTC)

mw.message library
I find the documentation for mw.message library confusing. Is the API just an interface to manage messages stored in the mediawiki namespace with fallbacks and extra stuff or can it be used to provide general localization for a LUA module?

If it is neither, then I would suggest adding an example to its use, even in a subpage if the reference manual is not the appropriate place for it.

Speaking of which, is there any API that facilitates localization of lua modules such as this: https://github.com/kikito/i18n.lua? If not, then that's my suggestion. — Preceding unsigned comment added by 197.218.81.244 (talk • contribs) 19:56, 13 December 2015 (UTC)
 * It is, as is stated in the documentation, an interface to MediaWiki's i18n system that involves the MediaWiki namespace. Somewhat more specifically, it wraps the PHP Message class. It could be used for general localization for a module, if the module is to be localized by creating MediaWiki-namespace messages. Anomie (talk) 14:34, 14 December 2015 (UTC)

UNIQ ... QINU Strip Marker
I'm trying to write a module that uses a DynamicPageList to select a random article from the list. I've found many different ways to call DynamicPageList, but no matter what I do, the module only sees a UNIQ ... QINU strip marker. If I unstrip it, I get nothing. What's the secret to reading strip content inside a Lua module? -- Dave Braunschweig (talk) 15:01, 29 December 2015 (UTC)


 * using frame:preprocess on the direct results worked for me (though I see one can't apparently do further processing on it without getting the marker again--I read that a parser function is supposed to avoid this problem that tags have, so maybe could rewrite the DynamicPageList function as one, but I got an error trying to change to setFunctionHook). Brettz9 (talk) 04:30, 12 March 2016 (UTC)

ustring.match problem
The function ustring.match (unlike mw.ustring.match) sometimes fails: ustring.lua:728: attempt to concatenate field '?' (a nil value) This occurs, for example, such code: This error has also on standalone Lua (without Mediawiki). I found a way how to get around, just to add a second capture: But it would be desirable that the error has been corrected.

Full example: Module:Ustring_test --StasR (talk) 16:20, 1 January 2016 (UTC)
 * Should be fixed once 261947 is merged and deployed. Anomie (talk) 15:50, 2 January 2016 (UTC)
 * Thanks! --StasR (talk) 21:05, 2 January 2016 (UTC)

Is result of frame:expandTemplate cached?
I call twice 'frame:expandTemplate' with the same parameters. Apparently, the template is executed only once. --StasR (talk) 17:09, 13 January 2016 (UTC)
 * Yes, calls to  for the same template with the same parameters are cached, unless the expansion sets the "isVolatile" flag. Anomie (talk) 15:28, 14 January 2016 (UTC)
 * Developer of the extension says he doesn't know how to do it. :-( --StasR (talk) 17:21, 14 January 2016 (UTC)
 * He might look at how the Cite extension does it, to learn by example. He could also ask for assistance, I'd recommend wikitech-l as a good place to start. Anomie (talk) 15:11, 15 January 2016 (UTC)

Is there a way to keep the original parameter order?
When iterating over  with , the original order of parameters is lost: if I use  , the parameters will swap positions (unnamed_arg will be the first, named_arg the second, as is always the case with unnamed & named parameters). But it is critical for me to keep the original order.

Documentation says: "For performance reasons, frame.args uses a metatable, rather than directly containing the arguments. Argument values are requested from MediaWiki on demand. This means that most other table methods will not work correctly, including,  , and the functions in the Table library".

Maybe I should overwrite  somehow, so that the original order will be kept? But I don't even know how to get the contents of that function ( gives "function"), let alone how it "requests argument values from MediaWiki on demand".

Thanks in advance. Jack who built the house (talk) 18:42, 13 February 2016 (UTC)
 * Jack who built the house, have you found a solution for this problem? Reptilien.19831209BE1 (talk) 12:53, 30 October 2017 (UTC)
 * Hm, for some reason the ping didn't work. Nope, I haven't. Probably a Phabricator task has to be created. Jack who built the house (talk) 04:33, 9 November 2017 (UTC)
 * Phabricator task. Jack who built the house (talk) 18:08, 16 June 2018 (UTC)

mw.ustring.match and ordering of combinations in character class
When studying Lua modules and regexes at the same time, I found this:
 * string.match( '314 159 265', '^[%s]*[%-]?[%s]*[%d]+[%d%s]*$' ) == '314 159 265'
 * string.match( '314 159 265', '^[%s]*[%-]?[%s]*[%d]+[%s%d]*$' ) == '314 159 265'
 * mw.ustring.match( '314 159 265', '^[%s]*[%-]?[%s]*[%d]+[%d%s]*$' ) == '314 159 265'
 * mw.ustring.match( '314 159 265', '^[%s]*[%-]?[%s]*[%d]+[%s%d]*$' ) == nil

In words: Two patterns differ in part  versus , each of two is tested with two functions (string.match and mw.ustring.match). Then  +   does not detect occurrences which are detected by other three combinations and which, as far as I currently understand it, must be detected. Is it a problem with my understanding or with current implementation of ? Stannic (talk) 15:55, 16 March 2016 (UTC)
 * This sounds like T73922. Anomie (talk) 13:28, 17 March 2016 (UTC)

fetchLanguageNames
Hi,<BR/> How should we call fetchLanguageNames to have all languages (include='all') with their languageName in their language (inLanguage ~ autonym) (719 languages).<BR/> Sadly fetchLanguageNames(Nil,'all') returns the same thing as fetchLanguageNames (417 languages in fact), when fetchLanguageNames('fr','all') returns 719 languages<BR/> Perhaps it is a bug or perhaps there is no way to get the autonym of the additional languages ?<BR/> Cheers Liné1 (talk) 13:43, 13 May 2016 (UTC)
 * This is due to MediaWiki's underlying Language class. It doesn't call the 'LanguageGetTranslatedLanguageNames' hook when fetching autonyms, so it doesn't get the additional languages from Extension:cldr in that case. A comment in the code says "TODO: also include when $inLanguage is null, when this code is more efficient". Anomie (talk) 16:03, 16 May 2016 (UTC)
 * Thanks for the answer. Best regards Liné1 (talk) 17:35, 16 May 2016 (UTC)

mw.loadData and next
as far as i know, the standard way to test if a lua table is empty is to test for. i will be happy to learn a better or safer way to test, but this is what many sources seem to indicate.

i have a module, let's call it "data module", that looks something like so: i then use it from another module like so: i guess it has something to do with the sanitation imposed by loadData. is this a bug? feature? intentional? unintentional?

presuming this is known and intentional, i think that at the least, the documentation should warn about it, and maybe provide some sanctioned alternative to  test.

peace - קיפודנחש (talk) 23:51, 13 June 2016 (UTC)
 * Extension:Scribunto/Lua_reference manual says: "The table actually returned by  has metamethods that provide read-only access to the table returned by the module. Since it does not contain the data directly,   and   will work but other methods, including ,  , and the functions in the Table library, will not work correctly." Matěj Suchánek (talk) 06:02, 14 June 2016 (UTC)
 * thanks. i guess i missed this piece in the documentation. it would be good, i think, if the metatable will add a method to test for emptiness, i think (t:empty returning bool or somesuch). also, maybe it would be better to throw exceptions when calling a "broken" method, rather than returning incorrect result. peace - קיפודנחש (talk) 15:45, 14 June 2016 (UTC)
 * The problem is that Lua 5.1 just doesn't have the ability to do what's being asked here. Even 5.3 doesn't seem to have a way to override, although you might be able to cheat on it by using   to get a next-like function. There's nothing we can do for the length operator, that would need 5.2. Anomie (talk) 13:14, 15 June 2016 (UTC)

Title objects: getContent versus exists
The page states that  is expensive and that   is not. Yet, aren't  and   equivalent, such that the latter is an inexpensive workaround? Are there situations where  would be required in its current form instead of the inexpensive workaround? Njardarlogar (talk) 08:56, 25 July 2016 (UTC)


 * "getContent" is expensive too. Taylor 49 (talk) 19:40, 23 March 2021 (UTC)

MediaWiki and looking into the entire module, Chapter edit using a browser while editing in the variable 'text', not only to this chapter
We have a code in Lua: Peering to the entire module, which can not watch via a browser is very easy, but when this module we watch and show his chapter on the browser during editing, it analyze his chapter, instead of the whole module in the variable  'text' , and I want to just analyze the entire module, not the section that edit. How to fix it.Persino (talk) 15:00, 18 August 2016 (UTC)

How to download precisely defined section of the module using the equipment in Lua on mediawiki
How do I bring a strictly defined section of the module using the equipment in Lua for mediawiki? Persino (talk) 16:01, 24 August 2016 (UTC)

Call mw.loadData with parameter
About mw.loadData writen that the data module is like require, can have functions. But how call it with a parameter? E.g.: Would be desirable that the module return different data depending on the parameter. (Alternative to make separate modules or to expand the table does not fit.) --Vladis13 (talk) 20:46, 16 October 2016 (UTC)
 * The returned table (and all subtables) may contain only booleans, numbers, strings, and other tables. Other data types, particularly functions, are not allowed. --StasR (talk) 07:26, 17 October 2016 (UTC)
 * The returned table - yes, but itself data module can have functions. E.g. work the following 'Module:data module': I want to it can process not only CurrentTitle, but any title that given via parameter, like in a usual module.  --Vladis13 (talk) 17:35, 17 October 2016 (UTC)
 * This means that the module will return a function. --StasR (talk) 08:49, 18 October 2016 (UTC)
 * It sounds like you want to have a normal module, loaded with, rather than a data module. Anomie (talk) 13:21, 18 October 2016 (UTC)

== To see the link in  than   --Rical (talk) 06:50, 24 November 2016 (UTC)

Translation of the reference manual
Hello,

I would like to help with a translation of the manual to Esperanto. But I see no "translate this page" link, as stated in Project:Language policy. Does the page already use the translate extension? If not, could an admin make the conversion? --Psychoslave (talk) 09:30, 25 November 2016 (UTC)
 * It was attempted in June by User:Amire80, but reverted a few days later by User:Shirayuki. Apparently it's harder than just letting an extension throw in 16K of weird comments. Anomie (talk) 14:18, 28 November 2016 (UTC)
 * It is very hard to prepare a huge page for translation. --Shirayuki (talk) 15:09, 28 November 2016 (UTC)
 * The page should be split into multiple pages at first. --Shirayuki (talk) 22:04, 29 November 2016 (UTC)
 * Well I can see the link, so I guess that someone made something but I just can see that in the history. So thank to whoever made something. :) --Psychoslave (talk) 07:06, 30 November 2016 (UTC)
 * Hmm, I fact it seems that only a very little part was actually translatable with the current translation markup… --Psychoslave (talk) 08:09, 30 November 2016 (UTC)
 * So having read some doc, I think the problem is that most of the text is not within a  anchor. I can add them, then some translate admin might validate the changes. I'll wrap the code too, as I see no reason to not translate it. That is the part that can be translated at least. The documentation should be adapted to what might concern the lectorate: having   instead of   is not a problem. However identifiers for example currently can't use unicode. So translating the source code only where possible enable to emphasize what is not translatable. Feedback is welcome on this point of view. --Psychoslave (talk) 10:47, 30 November 2016 (UTC)
 * Some administrator was too quick to validate the changes when most of the markup is still absent. As a result, most of already translated manually Russian version disappeared. Do you know some bot to put the markup automatically and move information from prrviois versions of the page to Translate chunks? Ignatus (talk) 11:13, 30 November 2016 (UTC)
 * After a reading of all the documentation I found on the matter, I would say that "no" for both your demands: there is no automatic way to have sliced  chunks. One might wrap the whole page in a single anchor, but this would probably provide awful chunks to translators. Regarding existing translation, they have to be manually migrated into the new system, see the migration process documentation for more information about that. But as far as I understand, to re-import the whole translation, all the original source need to be marked up and validated by a translator admin. Regarding the tag part, this is a work in progress. --Psychoslave (talk) 13:15, 30 November 2016 (UTC)
 * ✅ Maybe might have a look and mark the document for translation if everything seems fine. After that, it should be possible to migrate previous translations and make new ones with the help of the Translation extension. --Psychoslave (talk) 13:59, 30 November 2016 (UTC)
 * Why does something like  need to be wrapped in translate tags? The "math" is a Lua table name that's not going to work if you turn it into some other language, and the "atan2" is a function name that's similarly not going to work if altered. Do the "y" and "x" need to be translated? The wrapping of   in translate tags is even worse, are you going to somehow translate the ellipsis? Anomie (talk) 14:01, 30 November 2016 (UTC)
 * Whether the x and y should be translated is up to translators. There are other code sample where letting possibility to translate might seems more interesting like : table and key should be translatable in my humble opinion (but translators should be aware that identifiers should stay pure ASCII). So this is more consistent to make it translatable everywhere, the final decision being let to translators. From such a perspective, it's fine to remove from the translation list code chunks that only contains reserved keywords, like the example you give with ellipses. Most of the translate tags around code tags where added with a regexp, so this kind of case wasn't catch and removed in the process. --Psychoslave (talk) 14:45, 30 November 2016 (UTC)
 * The page should be split into multiple pages before translation. I taught by example, but you cannot prepare for translation. --Shirayuki (talk) 14:28, 30 November 2016 (UTC)
 * Why would you like to see the page split? Please provide more explicit explanations on expected benefits. There was already several translations based on the single page realized without the Translate extension, and now there is a tagged version for it. If there are specific problems with the proposed version, please detail what those problem are so it can be fixed, or fix them directly. --Psychoslave (talk) 15:00, 30 November 2016 (UTC)
 * The page is too huge to be prepared for translation at once. Untranslatable parts should be excluded finely for translators and translation admins. --Shirayuki (talk) 22:26, 30 November 2016 (UTC)
 * Ok, well, I didn't made any split so far, but I did progress on the adding tvar, and some other tricks. The current state of my progress is here, so my changes don't conflict with the main page. Please let me know if you can grab more problems to resolve on this version, I already know that I yet have to treat some links to tvar, but I'm not sure which one should be tvar-ed as "url" and which one should give opportunity to link to some translated pages. Namely this links are :
 * subst
 * MediaWiki-namespace messages
 * comments
 * UTF-8
 * double-precision floating-point value
 * E notation
 * NaN
 * closures
 * order of operations
 * syntactic sugar
 * lexical closures
 * syntactic sugar
 * tail calls
 * pseudocode
 * E notation
 * pseudocode
 * seed
 * regular expressions
 * PCRE
 * palindrome
 * $wgExpensiveParserFunctionLimit
 * substed
 * strip marker
 * Language code
 * IETF language tags
 * Extension:CLDR
 * wiki's local time
 * Extension:ParserFunctions
 * Help:Magic words
 * FAQ
 * Help:Magic words
 * Help:Magic words
 * Grammar
 * $wgScriptPath
 * $wgServer
 * $wgSitename
 * $wgStylePath
 * $wgDisableCounters
 * interwiki
 * protocol-relative
 * transcludable
 * scary transclusion
 * $wgExtraInterlanguageLinkPrefixes
 * HTML entities
 * strip marker
 * MediaWiki:comma-separator
 * MediaWiki:and
 * MediaWiki:word-separator
 * HTML entities
 * MediaWiki:ellipsis
 * strip marker
 * MIME type
 * expensive function count
 * Percent-encodes
 * Percent-decodes
 * Normalization Form C
 * Normalization Form D
 * Unicode character properties
 * bitwise operations
 * bitwise AND
 * bitwise complement
 * bitwise OR
 * bitwise XOR
 * shifted
 * logical shift
 * shifted
 * logical shift
 * arithmetic shift
 * rotated
 * Wikibase Client
 * Wikidata
 * Extension:Wikibase Client/Lua
 * ScribuntoExternalLibraries
 * ScribuntoExternalLibraryPaths
 * hook
 * UnitTestsList hook
 * Jenkins
 * Lua (programming language)
 * I don't need guidance about each, but what should I do for each class of link would help me. --Psychoslave (talk) 00:28, 3 December 2016 (UTC)
 * Hi, would you please take a look at this stub, and tell me if apart from links of form en:… and … , links seems fine for you. Also, how should this two kinds of links be prepared for translation? I think it would be better if the link would lead to the localized wikipedia article if it does exist, but I don't know how to do that. --Psychoslave (talk) 11:06, 6 December 2016 (UTC)
 * About, why did you make getmetatable translatable?--Shirayuki (talk) 11:55, 6 December 2016 (UTC)
 * Most tvar where added with a regexp, I didn't specifically wanted getmetatable to be translatable, it just that in the general case the label of the link should be translated. --Psychoslave (talk) 15:33, 6 December 2016 (UTC)
 * , I replace that and other similar cases with a tvar embedding the whole link. I also did some clean up for other cases where to my mind there is really nothing translatable. Please let me know if there are further improvement I could make on this regard. Also could you suggest me something for links toward the English Wikipedia like arithmetic shift and Lua (programming language) . --Psychoslave (talk) 08:36, 7 December 2016 (UTC)
 * Also, any of the translator adminstrators in, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , is welcome to make a review and feedback of this preparation for translation, and would it be fine as is, move its content in the current help article and mark it for translation. Also if there is an easier way to contact members of a group in the wiki, please let me know. :) --Psychoslave (talk) 14:32, 8 December 2016 (UTC)


 * If someone insists on splitting this page, please transclude the subpages back into this main page to preserve the ability to load one page and search it with Ctrl+F. Anomie (talk) 14:39, 1 December 2016 (UTC)
 * This looks like a good compromise. I was about to propose that. --Ciencia Al Poder (talk) 10:25, 5 January 2017 (UTC)

Hi, , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , could anyone provide feedback/mark the current version for translation? Also if there are a better way to highlight such a demand, please let me know. --Psychoslave (talk) 21:50, 28 December 2016 (UTC)

Bug in trim+gsub
=mw.text.trim( mw.ustring.gsub( '0u0', 'V', '' ) ) u =mw.text.trim( mw.ustring.gsub( '0u0', 'V',  ) ..  ) 0u0 =type( mw.ustring.gsub( '0u0', 'V', '' ) ) string --StasR (talk) 21:11, 9 December 2016 (UTC)
 * Not a bug. See T105754 for an explanation. Anomie (talk) 20:06, 10 December 2016 (UTC)
 * Thanks. Amusingly ) --StasR (talk) 01:47, 11 December 2016 (UTC)

proposal to add translation comments(translation unit markers)

 * Proposal:Add translation comments(translation unit markers,  etc.) after all translate tags and titles of all sections, subsections, and subsubsections. Purpose:Make all sections subject to translation. I have made a sample text( proposing speedy delete). You can see it here.(some translation tags and translation comments are removed)ツバル (talk) 02:06, 17 January 2017 (UTC)
 * I believe the Translate extension adds these automatically once someone actually marks the revision for translation. Anomie (talk) 15:27, 17 January 2017 (UTC)


 * (to user:Anomie) Please display Extension:Scribunto/Lua_reference_manual/eo, Extension:Scribunto/Lua_reference_manual/fr, Extension:Scribunto/Lua_reference_manual/ja, Extension:Scribunto/Lua_reference_manual/pl, Extension:Scribunto/Lua_reference_manual/ru, and Extension:Scribunto/Lua_reference_manual/uk. There are shown the message the translation is 100% complete. However, in fact most of these articles remain in English. The source revision of the translation is this revision. It has only 6 &lt;tranlation> tags and 6 &lt;/tranlation> tags and 8 &lt;!--T: tags. It causes the probrem. The purpose of my proposal is to eliminate this situation. Thank you!ツバル (talk) 03:02, 21 January 2017 (UTC)
 * I withdraw this proposal because I understood how to add &lt;!--T: tags. ツバル (talk) 12:17, 21 January 2017 (UTC)


 * As already explained, this proposal is going nowhere. &lt;!--T: tags are added when a translation admin marks the page for translation, and this won't be done because this page is very huge and very impractical to make it translatable, review changes, etc. The proposal a few sections before this one is to split this page in subpages so each part can be reviewed more carefully and make each one translatable on it's own. Making it translatable now would be a waste for all translators if it's going to be split, because translations will be lost (still recoverable from history but hard to restore on the new page) --Ciencia Al Poder (talk) 12:32, 21 January 2017 (UTC)


 * (To User:Ciencia Al Poder) I think that the problem was caused, because user:Shirayuki set the revision without enough &lt;translate&gt; tags as a translation source. Now user:Shirayuki is fixing the problem. So I will wait for user:Shirayuki's work. About &lt;translate&gt; tags and &lt;! - T: -&gt; tags, it is described only in "Help:Extension:Translate/Page translation administration" for translation administrators, but it is not described in "Help:Extension:Translate." I think it is unkind. Thank you.ツバル (talk) 13:14, 21 January 2017 (UTC)

Empty and blank string detection?
Hi, how can I write a conditional expression that detects whether an argument is empty? Ideally I want:
 * Parameter not set → false
 * Parameter set to empty string → false (important!)
 * Parameter set to blank characters only → false (would be nice to have)
 * Parameter set to any non-blank string → true.

This is quite useful for modules that are called by multi-level substitution, where parent templates by default stick an empty string into an undefined parameter, occasionally with extra blanks. Deryck C.Meta 15:25, 10 February 2017 (UTC)


 * This is a largely off-topic here, as it is a programming problem not a question related to the reference manual, Lua_Programming/Statements or Lua/Conditions should help with that. 16:32, 10 February 2017 (UTC) — Preceding unsigned comment added by 197.218.81.60 (talk • contribs)
 * Agreed about the location - this is probably better off at en:WT:Lua. But seeing as we are here, you could use a function like this:


 * This assumes that all of the values in the args table are strings (which they will be if you are using frame.args from an #invoke statement). To make that more convenient, you could put the args table in an upvalue:


 * Alternatively, if you use something like en:Module:Arguments, then you can do this:


 * By default, Module:Arguments treats whitespace arguments as, and if you need different behaviour it is easily customised. — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 09:49, 11 February 2017 (UTC)

safesubst:FULLPAGENAME equivalent
I've got another question: Is there a safesubst:FULLPAGENAME equivalent in Lua?

The issue at hand is that I want to create a Template:Temp1 which has. Then I want to be able to on some Page1. My desired result is that the template will subst "Page1" onto Page1. Currently, if I try to do

pframe = frame:getParent:getTitle

It gives me "Template:Temp1". Whereas

pframe = frame:getParent:getParent:getTitle

returns "Lua error in [Module name] attempt to index local 'pframe' (a nil value)."

Is there a solution to this problem? Or is this not an intended use of Lua and I should go back to using ? Deryck C.Meta 16:02, 10 February 2017 (UTC)

You can't get the grandparent (parent of a parent) of a frame (probably to avoid frame inception). The solution is simpler than wikitext, simply use Extension:Scribunto/Lua_reference_manual. — Preceding unsigned comment added by 197.218.81.60 (talk • contribs) 16:24, 10 February 2017 (UTC)


 * Thanks, this is great. The way to use it is tostring(mw.title.getCurrentTitle) and it works. Deryck C.Meta 16:46, 10 February 2017 (UTC)

Namespace collision with PageForms extension for Italian language
Possible collision with PageForms extension for Italian (eventually other languages as well). Please check here the details: Namespace_collision_with_Scribuntu_extension_for_Italian_language — Preceding unsigned comment added by Michele.Fella (talk • contribs) 11:48, 16 February 2017 (UTC)
 * This is the wrong place to report this issue. You should file a task in Phabricator. Anomie (talk) 13:33, 16 February 2017 (UTC)

parameter for scribunto-doc-page-does-not-exist
At Swedish Wiktionary, the $1 parameter for Scribunto-doc-page-does-not-exist seems to contain the Module: prefix. Is this intended behavior? Moberg (talk) 17:34, 27 February 2017 (UTC)
 * Yes. More specifically, it's the full title of the doc page constructed by applying the 'scribunto-doc-page-name' message. It's possible to locally customize this message if a wiki wants Scribunto doc pages to be something like "Help:Module documentation/$1" rather than "Module:$1/doc". Anomie (talk) 14:10, 28 February 2017 (UTC)

return "text" .. is_nil

 * This code:  results in an error : "Error Lua in Module:Central at line 194 : attempt to concatenate global 'is_nil' (a nil value).
 * This code:  solves the error.
 * Of course this is a bug in the Lua compiler: in a return, it not evaluates the expression, but it waits for an arguments list.
 * I create a task or you transmit it? --Rical (talk) 20:25, 7 March 2017 (UTC)
 * It seems extremely unlikely that your analysis here is correct. More likely is that you had an unnoticed typo or other bug in the first case and accidentally fixed it in the second. If you wish to pursue this, please provide a simple test case (not a link to a 1000-line module somewhere) that illustrates your claim. Anomie (talk) 15:18, 8 March 2017 (UTC)
 * Sorry, I was too tired. The error is really to concatenate a nil value. --Rical (talk) 00:21, 9 March 2017 (UTC)

Ustring error messages
The errors for the functions in the Ustring library typically include nothing more than a message, with no reference to module or line number. For instance, if I call, you get nothing more than Lua error: bad argument #1 to 'sub' (string expected, got nil). Could this be fixed?

It would be so much more helpful if it said, for instance, Lua error in Module: ModuleName at line x : bad argument #1 to 'sub' (string expected, got nil), the more informative error that  gives. — Eru·tuon 22:09, 11 March 2017 (UTC)

is there a place I should go to put in this request? — Eru·tuon 17:59, 13 March 2017 (UTC)
 * Bugs should be reported in Phabricator, with tag "MediaWiki-extensions-Scribunto". In this case, note that you can get a whole stack trace by clicking on the red error when JavaScript is enabled, as mentioned at Extension:Scribunto. Anomie (talk) 13:56, 14 March 2017 (UTC)
 * Oh, I never visited the main page, so I didn't know the error messages are clickable. That is very useful! Thanks. — Eru·tuon 23:57, 14 March 2017 (UTC)

Return CSS color code
I have a problem returning CSS color code from a Lua module: calling a function that return a color code (for example "#E1151F") the result is a newline followed by "1. E1151F", even if the call is in the middle of the line and not at the start.--Moroboshi (talk) 06:49, 27 April 2017 (UTC)
 * This would happen on a normal template, because that's syntax for ordered lists. Try output the code with &lt;nowiki&gt; tags (not sure if that would work). --Ciencia Al Poder (talk) 09:35, 27 April 2017 (UTC)
 * For reference, it's a very old bug: T14974. It's basically impossible to reliably have a template or parser function (like ) return a value beginning with certain characters including '#'. Anomie (talk) 13:21, 27 April 2017 (UTC)
 * Thanks! Usinng <nowiki ></nowiki> didn't work, but in the bug discussion there was the suggestion to return the html entity  and this worked.--Moroboshi (talk) 20:09, 27 April 2017 (UTC)

Translating prbolems (翻译问题)
Some of the content seems to be unabled to be traslated? I can't traslate some of the content into Chinese. Nothing is regarded to be untraslated, but in fact, much content is untraslated.--SolidBlock (talk) 09:28, 5 June 2017 (UTC)

mw.loadData with small tables
Performance-wise, how does  perform compared to a regular , when loading many times a small table (let's say, about 20 items)? Is it still performing better? Od1n (talk) 14:14, 28 June 2017 (UTC)

Translation problem
There is impossible to properly translate link to translatable section titles. For example content of section table links to section Expressions. However, in Polish variant in section table, the corresponding link is still presented as  (wyrażenie) instead of   (wyrażenie). Paweł Ziemian (talk) 20:31, 2 July 2017 (UTC)

mw.wikidata
Is not covered here. Is this because is not a standard? --Xoristzatziki (talk) 18:26, 10 July 2017 (UTC)
 * #Extension libraries (mw.ext) → Extension:Wikibase Client/Lua. It's an extension of Scribunto, extensions usually don't belong to the core documentation. Matěj Suchánek (talk) 14:11, 11 July 2017 (UTC)

Central recursive Test cases

 * The draft of Module:Central runs recursive Test cases = groups of groups of cases. Search "Library:testsCases".
 * Now I would connect them to Mediawiki Test cases, but:
 * that fails: class ClassNameTest extends Scribunto_LuaEngineTestBase
 * that fails: local testframework = require 'Module:TestFramework'
 * I also tried in my common.js:
 * class ClassNameTest extends ... but it give an error when I save it.
 * How to call Mediawiki Test cases in a module?
 * Are they some options to define somewhere? Could you do them if necessary in fr.wikisource? And say me which ones?
 * Where to find an efficient example? Thanks in advance. --Rical (talk) 05:02, 1 August 2017 (UTC)

How to make mw.log work?
I've got a typecheck in my function: But it throws me an error if I want to check type of  (which contains a string). I tried to insert  before that if, but it does not do anything. How are we supposed to use mw.log? --Dvorapa (talk) 12:10, 13 August 2017 (UTC)
 * I solved my issue using  on https://www.lua.org/demo.html, but mw.log should work somehow too. --Dvorapa (talk) 13:47, 13 August 2017 (UTC)


 * is printed either when you run an arbitrary code from the console or when you preview a page which executes the current module – then, you will see the output below the edit window under "Lua logs" ("Protokoly Lua"). Matěj Suchánek (talk) 14:57, 13 August 2017 (UTC)


 * At Dvorapa: you could check also if table.key is really always a string. Perhaps in some case it is not. --Rical (talk) 21:16, 13 August 2017 (UTC)

Weird behavior
Could someone check out wiktionary:Module:User:Suzukaze-c/ref test? Am I using  wrong or have I come across a bug? Suzukaze-c (talk) 10:40, 1 September 2017 (UTC)
 * You need to include the output from  (i.e. the   variable) in the wikitext returned from the module if you want the ref's superscripted number to show up. As for the references showing up in the references section despite the superscripted numbers never appearing, that's more of an issue with Cite than with Scribunto. Anomie (talk) 13:27, 1 September 2017 (UTC)
 * My problem is the latter. What should I do? Suzukaze-c (talk) 20:44, 1 September 2017 (UTC)

I got rid of my original problem by not generating ref tags I don't need. Now I have a new problem, where the d reference template is not regarded as equal to the same template used manually in text, resulting in defined multiple times with different content problems. Suzukaze-c (talk) 07:09, 15 September 2017 (UTC)


 * Fixed. :expandTemplate was not necessary; does expand things itself? Suzukaze-c (talk) 07:42, 13 December 2018 (UTC)

comp function in table.sort
Is there a reason why the comp function is explained using the statement (to paraphrase) " returns  " rather than "  returns  "? Are there situations in which one would be true but the other would not? If not, I think the more straightforward statement (the one not involving negation) is preferable. — Eru·tuon 00:02, 9 September 2017 (UTC)


 * I also though this, but there's a situation where it's not the same. If both elements to compare are equal, comp must return false, so once the table is sorted, elements that are equal will return false. Example: 1, 2, 3, 3, 4, running comp(a[i], a[i + 1]) will give true, true, false, true. Running the same comparison in reverse order will return false consistently. --Ciencia Al Poder (talk) 08:53, 9 September 2017 (UTC)
 * Thanks! I also looked up sorting functions and it looks like they might use the  function negated with the keys supplied as arguments in reverse order. I don't quite understand how it works yet (and I guess the actual function is written in C), so I'll just accept that. — Eru·tuon 07:03, 12 September 2017 (UTC)

Color issue
There is a color issue with this part of the manual for other language, as it's nearly the same color as outdated translation (example in the polish version at the moment). <blockquote style="border:1px solid grey; padding:0 0.5em;"> Note that this will not work: <pre style="background-color:#fcc"> local factorial = function ( n ) if n <= 2 then return n   else return n * factorial( n - 1 ) end end

I suggest to replace the problematic pink background color to a grey font color, that way this code is less in evidence : <blockquote style="border:1px solid grey; padding:0 0.5em;"> Note that this will not work: <pre style="color: #666;"> local factorial = function ( n ) if n <= 2 then return n   else return n * factorial( n - 1 ) end end Does someone have a better solution ?

--Zebulon84 (talk) 13:39, 19 September 2017 (UTC)
 * Your suggested grey doesn't score as well on this color contrast tool. Anomie (talk) 12:41, 20 September 2017 (UTC)

Why is string.match 15x slower than my super-equivalent function using string.find and string.sub?
I made the follow function, which is super-equivalent to  : I said super-equivalent because, unlike string.match, my fsub will accept a 4th argument as used by string.find. As demonstrated by the following benchmark, fsub runs ~15 times faster than string.match: Output: 0.030277667 seconds, string:sub(string:find(pattern)) 1.033540901 seconds, string:match(pattern) 0.069701356 seconds, fsub(string, pattern) true	true	ghijkl true	true	NG123	123	-- comparing returns of fsub and string.match Perhaps we should replace string.match with fsub in scribunto (though maybe making the 4th parameter do nothing to ensure absolute compatibility). Such should greatly reduce the lua usage time of modules that use string.match heavily. -Codehydro (talk) 20:25, 23 September 2017 (UTC)
 * By the way, I want to help make Scribunto better. I have several ideas that I believe would greatly improve some mw libraries. How can I join the development team? Codehydro (talk) 20:41, 23 September 2017 (UTC)
 * Making string.match 15x faster sounds like a good idea. :) That should be proposed as a new task in Phabricator, which is where most Scribunto development is discussed. As for how to contribute, you're looking for the How to become a MediaWiki hacker page - in particular the links to Developer access, MediaWiki-Vagrant and Gerrit/Tutorial. You should check out the Scribunto project in Phabricator as well - there are lots of tasks there that could use some love. Best — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 01:56, 24 September 2017 (UTC)
 * I note that  and   are both implemented in C in Lua 5.1, not implemented by Scribunto at all. The difference in performance is because   forces "plain" mode if the pattern doesn't have any special characters, while   doesn't. You'd have to ask upstream if there's a reason they don't apply a similar optimization to   or if they just never got around to it. If you change your pattern to something like ,   is faster.
 * You're welcome to contribute to Scribunto by submitting tasks in Phabricator and patches in Gerrit, but you should first spend some time reviewing existing tasks and design decisions (as well as our coding conventions, particularly those for Lua) to make sure your ideas aren't contrary to the goals and constraints of the extension. Anomie (talk) 13:38, 25 September 2017 (UTC)

Letting translators decide translation granularity, even in code portion
Hello. I don't agree with you that no translation should be happen within code examples. Sure their are part which, so far, can't be translated (like keywords), but I had already begin to document what could, and what couldn't be translated at the translator discretion. This especially makes sense for comments part, but translators should be free to translate any other part which remains technically valid. All the more, people do code with locale language in practice (example), so that's seems really incongruous to forbid the practice in the documentation. If you do have some grounded arguments to completely forbid translation in code portion, please reply to expose them. Otherwise, please let translators decide what they ought to translate or not according to their knowledge of what their target community is accustomed. --[[User:Psychoslave|Psychoslave (talk) 12:49, 30 September 2017 (UTC)


 * I think translating code examples is a bad practice, hard to translate and easy to make typos, This page is already very big to translate, I think adding more fuzz to it wouldn't help translators. But I'm not going to revert you again if you decide to make it translatable again. --Ciencia Al Poder (talk) 14:55, 30 September 2017 (UTC)
 * Once again I think it should be up to translators whether they should or not translate code examples. Giving the option is not enforcing the practice, so if translators of some language find it unworthy to translate it, they can just use the "duplicate" button and save. --Psychoslave (talk) 07:56, 2 October 2017 (UTC)

Date of page creation and size
Is it possible to get the date of creation of a page and its size at the time of creation? --Tobias1984 (talk) 14:11, 22 October 2017 (UTC)
 * No. Matěj Suchánek (talk) 07:46, 23 October 2017 (UTC)
 * That would be useful for tables that track writing contests. Hopefully such a feature can be added at some point. --Tobias1984 (talk) 16:52, 23 October 2017 (UTC)
 * I suggest to create a Scribunto extension for that. --Valerio Bozzolan (talk) 22:14, 23 October 2017 (UTC)

Link tokens to their section of the manual
If would be nice if the tokens were links to their sections of the manual. Lady Aleena (talk) 00:58, 3 December 2017 (UTC)

What means RANK_TRUTH, RANK_PREFERRED ... ?

 * RANK_TRUTH, RANK_PREFERRED... seem not enough described.
 * What means each of these RANK? in which case are they usefull?
 * What they change when a Lua coder uses RANK_PREFERRED?
 * What happens if the Lua coder select another one of them? --Rical (talk) 21:12, 5 February 2018 (UTC)
 * You are probably referring to Extension:Wikibase Client/Lua. See d:Help:Ranks for what they mean. Matěj Suchánek (talk) 10:08, 6 February 2018 (UTC)
 * I continue this talk in Extension talk:Wikibase Client/Lua --Rical (talk) 15:13, 7 February 2018 (UTC)

isRedirect property across wikis
Is it possible to use the isRedirect property of title objects to detect whether a page in another wiki is a redirect? I'm trying to resolve a problem in Wiktionary, where we want to determine if an image should be displayed depending on whether the file is redirected in Commons. The module where this is attempted to be used is wikt:Module:zh-glyph, and here is some relevant discussion for more background: commons:User talk:Justinrleung, commons:User talk:Wargaz. Justinrleung (talk) 22:44, 25 April 2018 (UTC)

Title object and spurious links
At present, the Title library section documents the creation of a title object and notes four properties that, when called, record the page as a link. The four properties documented are:,  ,  , and. The recording of the spurious link causes problems when testing whether a given label corresponds to a redirect on Wikipedia in order to link to it. That is because if the label actually corresponds to a dab page, then that dab page is recorded as having an incoming link, even though the code does not create a link in that case.

Today I tried to circumvent that problem by testing the  property instead, as that is not documented as recording a spurious link. Before I did, I checked that merely creating the title object did not itself trigger the recording of the link (otherwise there would be no point in looking at other properties). Finding that creating the title object alone did not record a link, I went ahead and tested the  property. Disappointingly, that also created a link. I think it would be useful to update the documentation here to show which properties actually trigger these spurious links, and save other editors wasted time in performing the sort of tests I've done today. Or better yet, fix the problem by ensuring that links are not created simply by the act of testing whether a particular title is a redirect. --RexxS (talk) 14:30, 31 May 2018 (UTC)
 * I think it would be useful to update the documentation here to show which properties actually trigger these spurious links That has been done.
 * Or better yet, fix the problem by ensuring that links are not created simply by the act of testing whether a particular title is a redirect. Doing that would mean that, if the target page's status changed, other pages checking the page's status in Lua would not be properly updated. Anomie (talk) 16:20, 31 May 2018 (UTC)
 * I'm still waiting to hear your justification for calling my edit "incorrect". It is clear that  causes exactly the same problem, but your attempt at revising the documentation fails to recognise that. My testing to confirm the issue is available at en:User:RexxS/sandbox/Wikidata, and I'd be happy to explain how to the test works. Where's the test to support your assertion?
 * As for You don't need to record the expensive call in the link table. There is no reason whatsoever why a different table could not be used which did not produce the side-effect of making spurious links. This bug renders the title library useless in any Wiki because other editors will not put up with links to dab pages being made when code checks for a redirect. --RexxS (talk) 16:35, 31 May 2018 (UTC)
 * It seems you overlooked the link in my edit summary showing that your assertion is incorrect. Here it is again.
 * Using your own test case, observe that this does not produce a link with the current version of en:Module:WikidataIB/sandbox, only a transclusion. The current version of en:Module:WikidataIB does produce a link (test), but that's because it uses  rather than  . Don't be confused by the fact that Special:WhatLinksHere merges wikilinks and transclusions together.
 * There is no reason whatsoever why a different table could not be used Well, except for the fact that the different table would have to be created in the first place, and then every page on every wiki would have to be reparsed to populate it, and then all the code would have to be updated to use the new table. All to avoid using the existing tables for one of the main purposes they exist for. But if you want to follow up on that, take it to Phabricator. T14019 is probably the most relevant task.
 * Anomie (talk) 18:11, 31 May 2018 (UTC)
 * Anomie (talk) 18:11, 31 May 2018 (UTC)

== mw.text.unstrip for extracting }}

Seems like  returned an empty string. This follows on to some questions: • speedy • 🔔&#xFE0E; • 🚀&#xFE0E; • 10:48, 22 June 2018 (UTC)
 * 1) Does that function work with
 * 1.19 is really old. Most parser tags, including, generate "general"-type markers.  will only unstrip "nowiki"-type markers, "general"-type markers cannot be unstripped. See  and  for background on that. Anomie (talk) 13:15, 22 June 2018 (UTC)
 * Ah I see. Our host has a heavily modified fork with more of a social/SOA lean on it, but I can understand the apprehension.
 * Hmm, no unstrip then. That leaves me the possibility of getting +parsing the output (or botting the wiki). Is there some way I could feed the highlighted HTML to other functions as a string?
 * Thanks for the explanation so far. • speedy • 🔔&#xFE0E; • 🚀&#xFE0E; • 13:38, 22 June 2018 (UTC)
 * Update - seems like botting out the parser tag and substing my extractor everywhere works. No longer in need of mw.text.unstrip :) • speedy • 🔔&#xFE0E; • 🚀&#xFE0E; • 09:25, 23 June 2018 (UTC)

This message misses of line number: Error Lua : ')' expected near '='

 * In my case it happens in a if with a single '=' as operator.
 * Thanks in advance to change it. --Rical (talk) 09:06, 10 July 2018 (UTC)

should be dicouraged
The older  should be dicouraged in favour of the newer   with much more functionality. This is targetting only at this manual etc., but does not impose any change in code base. Greetings --PerfektesChaos (talk) 08:16, 4 August 2018 (UTC)
 * It is confusing to encounter an unknown function while  became rather popular.
 * offers a world of additional capabilities.
 * People should not insert new calls.
 * Some older usage may adopt  when revising modules anyway.
 * No deprecation planned for the next two eternities.

How to code a clickable button
I have tries for 3 weeks to insert a clickable button in my central module. But it seems impossible inside Lua. I already tried https://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_onclick -- and -- https://jsfiddle.net/rjpo5za7/16/ -- and -- http://jsfiddle.net/3epbnhg6/3/ -- and -- in whole MediaWiki but without success. Have somebody an efficient solution?
 * You cannot insert aribitrary JS to pages using Lua, no. Consult Manual:Interface/JavaScript. Matěj Suchánek (talk) 12:55, 21 August 2018 (UTC)
 * I am very desolate because my Central module contains many dropboxes and sortable tables using buttons to click and they are based upon local templates.
 * This imply to install them in all wikis at the same time as central modules.
 * This could probably need a new Phabricator task? --Rical (talk) 05:58, 22 August 2018 (UTC)
 * Fwiw, I've been working on gadgetry to support interactive wiki pages. (See n:Help:Dialog, n:User:Pi zero/essays/vision/sisters.) --Pi zero (talk) 02:39, 31 August 2018 (UTC)

"isSubsting" -- is that a spelling error?
"isSubsting" should be "isSubstring", obviously, but is that just a wiki page spelling error, or is it a problem in actual code? Equinox (talk) 23:40, 6 September 2018 (UTC)
 * Check the description: "Substing" → from "substitute". Matěj Suchánek (talk) 07:25, 7 September 2018 (UTC)
 * More specifically, from the "subst:" wikitext syntax used when substituting templates. Anomie (talk) 13:05, 7 September 2018 (UTC)

From the context of a template
This page says: "It's generally a good idea to invoke Lua code from the context of a template".

Why?

Is it really good to add a template layer between the article and the module?

One explanation that appears here is that is "avoids the introduction of additional complex syntax into the content namespace of a wiki", but is an "#invoke" much more complex than a template? --Amir E. Aharoni (talk) 19:53, 22 September 2018 (UTC)


 * Exposing that entry point to end users was probably a design flaw. There are many issues:
 * No templatedata for scribunto
 * Bad design of error messages -  try  . The error message is pretty bad, and there is absolutely nothing that users can do to improve it if it is invoked directly. A similar thing happens for the invoked function, unless proper error handling is added with reasonable error messages. Imagine that stuff showing up on a tool like visualeditor.
 * Some lua modules can be used just as meta-modules (or libraries), and don't really output anything useful when functions invoked directly. The invoke makes no such distinction and will fail. While templates can be coded in a similar manner, they are easier to understand, and at worst will output some gibberish.
 * Close to infinite parameters - With templates editors must deliberately code each and every single parameter in the source. It basically self documents itself to an extent. Lua,on the other hand, allows random parameters that can be hard to document, and harder to show in tools such as visualeditor or wikitext editor that supports such parameters.
 * Lua isn't localized (despite being created by native portuguese speakers). People who use such modules directly will need to be aware of its english error messages.
 * Such issues are especially problematic in wikis with "unpopular languages" were scribunto is probably not localized at all. — Preceding unsigned comment added by 197.235.53.108 (talk • contribs) 10:22, 24 September 2018 (UTC)
 * No, it was not a "design flaw". It's how wikitext templates work. As for your numbered list,
 * That could in theory be done by putting the templatedata on the module's documentation page. I don't know how useful that would be at this time though.
 * You use bad syntax and the error message tells you what the problem is: "". You seem to be confusing it with  or , which produce the errors for the missing module or function that you seem to be expecting. And neither seems worse than  , which generates a redlink rather than any sort of error message.
 * You claim the broken output of meta-templates is somehow "easier to understand", although I see no evidence for that assertion.
 * Unlimited arguments are a feature. While "self-documenting code" is nice to have, it's no substitute for real documentation, and you seem to be greatly overestimating the extent to which wikitext templates can be considered "self-documenting" rather than "self-obfuscating".
 * This is a valid criticism, but it's an upstream issue. Without rewriting Lua there's nothing we can do about this.
 * Anomie (talk) 13:54, 24 September 2018 (UTC)
 * Avoiding the introduction of complex syntax into articles is the primary reason. Editors generally understand templates and are pretty used to seeing . Replacing the "Some template name" with "#invoke:A Module|a function", particularly with the pipe in there, could get confusing. Anomie (talk) 13:54, 24 September 2018 (UTC)
 * Anomie (talk) 13:54, 24 September 2018 (UTC)
 * Avoiding the introduction of complex syntax into articles is the primary reason. Editors generally understand templates and are pretty used to seeing . Replacing the "Some template name" with "#invoke:A Module|a function", particularly with the pipe in there, could get confusing. Anomie (talk) 13:54, 24 September 2018 (UTC)

wgUserLanguage
I'm wondering there seems no equivalent for this simple JS variable. The only thing I found is workaround with an expensive parser function  (which is not the same as  ) Is that really true? → User: Perhelion 10:24, 2 October 2018 (UTC)
 * Making that variable available from JS won't fragment the parser cache, while making it available in Scribunto would. See also T4085. Anomie (talk) 13:07, 2 October 2018 (UTC)
 * Thanks, that's remarkable, this task is under ongoing discussion since 2005. → User: Perhelion 20:36, 5 October 2018 (UTC)

What is a frame?
What exactly is a frame? I know it's in a table and is surrounded by round brackets, but what are they? What are they for? Where can I learn more about them? —CaiusSPQR (talk) 20:21, 13 January 2019 (UTC)
 * See Extension:Scribunto/Lua reference manual. It's an object which gives Lua modules the ability to transform wikitext. Matěj Suchánek (talk) 09:01, 14 January 2019 (UTC)
 * More generically, you might read Call stack or https://stackoverflow.com/questions/10057443/explain-the-concept-of-a-stack-frame-in-a-nutshell. Anomie (talk) 14:52, 14 January 2019 (UTC)

Patterns: add note to write "%1" not "$1"
Section #Patterns nicely notes that the escape-character is " " (not " " as in REGEX). I suggest a similar note to be placed in #Captures: use " " not " ". -DePiep (talk) 10:47, 22 January 2019 (UTC)
 * Regular expressions don't use  for backreferences either, so that wouldn't be appropriate. Some engines, including JavaScript and PCRE, do use that syntax in the replacement strings for functions such as   or   (although others, such as sed, use   in replacement strings too). If a note were to be added, it would be placed in #string.gsub. Anomie (talk) 14:25, 22 January 2019 (UTC)
 * Strange approach. You probably wanted to say "Regex does not use ... always", since your next sentence already describes situations where Regex does. Thereby you are missing the point. The proposal is to add a genetal note that says "in patterns, captures are identified by " since that is the variant Lua uses. Also about being generic: captures are not only used in  . I don't see why you would want to clarify its usage only in a detail not in the generic description of captures. -DePiep (talk) 15:42, 22 January 2019 (UTC)
 * You aren't differentiating regular expressions and functions that use regular expressions to find text for replacement. I know of no regular expression engine that uses "$1" with special meaning inside the regular expression itself, only in the replacement string.
 * The general note you now request is already present at #Pattern items: ", for n between 1 and 9; such item matches a substring equal to the n-th captured string (see below)".
 * Yes, captures are used in other places. But gsub is the only method doing a replacement, and replacement strings are the only place where you might see "$1" used in other regular expression libraries. That "$1" was your original point in this section, remember. Anomie (talk) 14:18, 23 January 2019 (UTC)

Patterns: pipe character literal issue
This might be of wider wm interest. Using patterns on enwiki, it appears that one cannot use  in a pattern to check for the literal pipe symbol. The solution is to use  in the pattern (see talk).

I cannot test mw that easily for this, but it might be worth notifying Lua using editors in other affected wikis. Is this manual the right place? It could save some time & frustration wikiwide. -DePiep (talk) 12:27, 22 January 2019 (UTC)
 * Note that this is specifically regarding passing the pattern as a parameter from wikitext, using a module such as w:en:Module:String, as is the case for any other template parameter that needs to contain a pipe character (outside of nested wikitext constructs such as links and template invocations). In Lua itself, you don't and can't use.
 * Personally I don't think it's worth mentioning here, any more than it's worth mentioning that you'd also need to escape an  in the wikitext when using unnamed parameters, or that you'll often have to escape   or   or various other wikitext bits in the wikitext to prevent them from being interpreted. Anomie (talk) 14:15, 22 January 2019 (UTC)
 * I agree. This is pertinent to all MediaWiki transclusions, not just Scribunto in particular. Nardog (talk) 23:23, 22 January 2019 (UTC)
 * See the examples: I am escaping the character in the pattern, with a  as prescribed in this manual.  -DePiep (talk) 15:47, 22 January 2019 (UTC)
 * You're confusing escaping in wikitext with escaping in Lua patterns. They are two different things. Anomie (talk) 14:19, 23 January 2019 (UTC)

call mw.getCurrentFrame results in a nil value
My central module uses mw.getCurrentFrame — Preceding unsigned comment added by Rical (talk • contribs) 22:32, 7 February 2019 (UTC)
 * Since some hours this use returns the error:
 * "Erreur Lua dans Module:Centralizer à la ligne 6784 : attempt to call field 'getCurrentFrame' (a nil value)."
 * That could be due to the change of the mediawiki version "1.33.0-wmf.16 (f75c676)" that I seen at "2019-02-07T23:04:00".
 * To reproduce this use yourself in any module the function mw.getCurrentFrame.
 * Can't reproduce, works fine when I try using  in a module on enwiki. Also the only changes in Scribunto from wmf.14 to wmf.16 are localization updates ( and ). Anomie (talk) 14:20, 8 February 2019 (UTC)


 * That is strange. Today I will build a dedicated module to test it.
 * I don't understand how mediawiki can be different in one wiki.
 * Perhaps a simple new copy in fr.wikisource could repair the bug.
 * I continue to make my test, else if a new copy repair it. Best regards --Rical (talk) 08:00, 9 February 2019 (UTC)

ScribuntoExternalLibraries Hook
Is this hook valid? Doesn't seem to be working.

Using URL parsed arguments in Lua templates?
Hi,

I would like to create a Lua template that is give some data analysis on a Wikidata item, but I don't want to create one page per item. What I would like to do is to create a dynamic tool that take a Wikidata item Qid as un URL parameter and render it.

Is it possible to get parameters from the URL in a Lua Template and how ?

Regards

--Thibdx (talk) 22:50, 20 March 2019 (UTC)

gsub error emitted by mw.text.trim
will generate: From a debugging perspective, this is pretty misleading. Are we able to make the error message more useful to the user (which could benefit the rest of the mw.text.* library and possibly others?)? ~ Tom.Reding (talk ⋅dgaf) 03:07, 15 May 2019 (UTC)
 * Created .  ~ Tom.Reding (talk ⋅dgaf)  15:53, 6 June 2019 (UTC)

version information in documentation
it would be helpful for the documentation to note the first version specific library was added to scribuno. many (most?) were grandfathered, but many others were added over time, so they may be available on version X but not X-1.

e.g., i just noticed mw.hash library, which was added to the documentation around july 2016, and added to scribunto itself at some mystery version. it would be helpful if the documentation page would mention next to a library (and next to functions, when those were added later) something like "Available since version XX" or "version XX wmfYY", or somesuch.

peace — Preceding unsigned comment added by קיפודנחש (talk • contribs) 17:17, 11 June 2019 (UTC)
 * If someone wants to dig through the code and extract that information, feel free. Note Scribunto itself it's really versioned, but going by the REL1_XX branches ("for MediaWiki 1.XX") would probably be good enough. Anomie (talk) 13:39, 12 June 2019 (UTC)

isRedirect is expensive but redirectTarget isn't
This seems counterintuitive. Is there a reason behind this? Nardog (talk) 19:49, 11 June 2019 (UTC)
 * The reason is because of the way the two are implemented, but that's not a very satisfying answer. The way isRedirect is implemented has historically been considered expensive for similar operations in extensions like ParserFunctions, while the way redirectTarget is implemented is based on the logic for template transclusion which hasn't historically been considered expensive. Anomie (talk) 13:47, 12 June 2019 (UTC)
 * Thanks for your answer. So if one replaced isRedirect with redirectTarget, would that actually reduce the server load? Nardog (talk) 13:55, 13 June 2019 (UTC)

Title object and pagelinks
Creating title objects with either mw.title.new or makeTitle seems to create an internal page link to the title. Is there currently any way to avoid this when checking if a page exists?

My code is something like this: Strainu (talk) 05:31, 12 June 2019 (UTC)
 * No, there's no way to avoid this. The link is recorded so MediaWiki can know to reparse the page if the target is created or deleted. Anomie (talk) 13:44, 12 June 2019 (UTC)
 * Thanks! So what happens if I do something like ? As far as I know ifexists does not add a link. Is there any drawback to using this construct except for the more complicated code?  Strainu (talk) 16:41, 12 June 2019 (UTC)
 * does add a link, and for the same reason. Anomie (talk) 13:16, 13 June 2019 (UTC)

Subpages
Hey guys, is there a way to get subpages of a page? --Dvorapa (talk) 08:56, 25 June 2019 (UTC)

mw.text.jsonDecode
documentation says: mw.text.jsonDecode( s ) mw.text.jsonDecode( s, flags )

Decodes a JSON string. flags is 0 or a combination (use +) of the flags mw.text.JSON_PRESERVE_KEYS and mw.text.JSON_TRY_FIXING.

Normally JSON's zero-based arrays are renumbered to Lua one-based sequence tables; to prevent this, pass mw.text.JSON_PRESERVE_KEYS.

To relax certain requirements in JSON, such as no terminal comma in arrays or objects, pass mw.text.JSON_TRY_FIXING. This is not recommended. however, on some wikis, maybe all, in wikimedia space (i.e., wikipedias), it seems that this function executes as if mw.text.JSON_TRY_FIXING is requested, and it may not even be possible to request "strict" parsing. calling  will parse to legit table with [6,7,8], ignoring the illegal comma after the 8 in the json string. demo: notice the extra comma after the 8, no flags are passed, but calling   returns , so the parsing was relaxed even though no flag was given (it behaves the same when passing zero explicitly).
 * Module:Illegal-json-parse-demo contains the following:

peace - קיפודנחש (talk) 22:41, 28 July 2019 (UTC)
 * That's a bug in HHVM's JSON parser, it doesn't follow the JSON specification in the first place. See also T214984. Anomie (talk) 12:17, 31 July 2019 (UTC)
 * thanks. i see. however, this is something worth mentioning in the documentation, because this is the way it behaves now. peace - קיפודנחש (talk) 05:47, 2 August 2019 (UTC)

Categorization
Many modules are difficult to find because they have no documentation, the only possibility to categorize them. Subpages cannot be documented, and not categorized. As a sequence, all sandboxes are uncategorized. It might be useful to collect all sandboxes in a category like e.g. C:Category:Scribunto module sandboxes. Would it be possible to collect automatically all modules with names ending with ? Sarang (talk) 07:08, 14 October 2019 (UTC)
 * This does not seem like an issue for discussion on this page. Lack of documentation for on-wiki modules should be fixed by adding documentation; discuss that further with your local community. I do not know why you claim subpages cannot be documented or categorized. Scribunto has no concept of "sandboxes", and adding one seems unlikely to be useful, particularly not for any sort of automatic categorization. Anomie (talk) 12:42, 15 October 2019 (UTC)

mw.uri.new.userLanguage
https://www.mediawiki.org/w/index.php?diff=3545271&oldid=3505728 Couldn't find this in master or wmf/1.35.0-wmf.8 branches; it's mentioned in https://phabricator.wikimedia.org/T68051. --BryghtShadow (talk) 03:13, 29 November 2019 (UTC)
 * Wishful thinking would be my guess, hoping that inserting it into the documentation would somehow resolve the issues preventing it from being implemented. Thanks for checking and reverting it. Anomie (talk) 13:14, 2 December 2019 (UTC)

mw.ext.data.get and mw.loadData
I had hoped to find some more information about how to use tabular data (from Commons). It looks like too many calls of mw.ext.data.get on one page cause an extreme increase of the Lua time usage and I was wondering if that could be resolved by somehow using mw.loadData; with the cases documented on this page I could not find a way though. Regards, XanonymusX (talk) 18:23, 9 December 2019 (UTC)
 * If it's always loading the same thing with mw.ext.data.get, you could potentially make a module that contains just  and load that module with mw.loadData. Although it might be more straightforward to see if the developers for Extension:JsonConfig would build in similar caching for that case.
 * If each call to mw.ext.data.get is loading a different data set, mw.loadData wouldn't help you. Anomie (talk) 14:07, 10 December 2019 (UTC)
 * Thanks, I have tried to do it that way now. The time usage is reduced, but still high (7+s on just one page); instead of Scribunto_LuaSandboxCallback::get it is now dataWrapper <mw.lua:661> and <mw.lua:683> that cause most of the timing issues. Is it really that expensive to load a data table (has only 48 entries in my case)? In that case there should be some kind of warning somewhere, I did not see the problem coming at all. Otherwise I might be doing something totally wrong. Luckily I have it only on testwiki and not already on Wikipedia ...--XanonymusX (talk) 00:18, 11 December 2019 (UTC)

Strange Error : cannot use '...' outside a vararg function ?
Like you know I work on the Module:Centralizer in French WikiSource and in Lua we always can code : function XXX.dropbox(selector, ...) local args = {...} ...... and so on But, from today, this results in an error : Erreur Lua in Module:Centralizer at ligne 9729 : cannot use '...' outside a vararg function near '...'. No further details are available.

I would like to know your test result rather than declaring a new Phabricator task in case I have misunderstood something.

Rical — Preceding unsigned comment added by Rical (talk • contribs) 18:57, 2 February 2020‎


 * This error occurs when you try to use varargs as an upvalue from an internal function. I managed to recreate it using this code:


 * If you run, you get the error "Lua error at line 5: cannot use '...' outside a vararg function near '...'." However, I didn't see any code in s:fr:Module:Centralizer that has this problem. Line 9729 doesn't have any varargs in at all, so I'm not sure what to make of that. Are you able to reproduce the error? Best — <span style="color: #194D00; font-family: Palatino, Times, serif">Mr. Stradivarius  ♪ talk ♪ 11:48, 5 February 2020 (UTC)

mw.message.parse
From the documentation: mw.message.rawParam

Wraps the value so that it will not be parsed as wikitext by. However, the method parse is not available (attempting to call it throws and it isn't documented), so the purpose of  is not clear. --Matěj Suchánek (talk) 13:10, 29 February 2020 (UTC)
 * Hmm. Yeah, there's probably not a whole lot of point to it without an equivalent of MediaWiki's Message class's  method. Anomie (talk) 14:01, 2 March 2020 (UTC)

Unit testing
Hello, I found eventually this discussion page. Is there any method to perform unit testing on LUA code? Has someone an example? Thank you. Psemdel (talk) 11:05, 22 March 2020 (UTC)
 * I saw at least two third-party frameworks for this: w:Module:ScribuntoUnit, w:Module:UnitTests. --Matěj Suchánek (talk) 14:48, 22 March 2020 (UTC)
 * I will give it a try. Psemdel (talk) 06:41, 26 March 2020 (UTC)

Configuration variables
When I tried everywhere to find some information about I had not been successful. I just could see that 'wgUserLanguage' won't be provided, the same may be with 'wgUserName'. Some very essential variables are accessible as well in templates as in JS; are they somehow available too in Lua? When they cannot be accessed within Lua, I will need to pass the values as #invoke-parameters. -- sarang ♥ 사랑 07:51, 17 July 2020 (UTC)
 * 'wgNamespaceNumber'
 * 'wgPageName'
 * Read about Title library and use  or   to access the data from Lua. Paweł Ziemian (talk) 21:39, 17 July 2020 (UTC)

First line
The first line is "local p = {}" but the only explantion is "p stands for package". Is the first line always this or are there other things it can be - something else other than "local" or other than "p", or something in the brackets? Peter James (talk) 15:03, 12 August 2020 (UTC)


 * @Peter James: Each module must return a table with data or functions to call. As long as the code does not break, it is insignificant how this "export" table is created.  somewhere at the top and   at the very bottom is just a common coding style but this variable can also be   or  . --Matěj Suchánek (talk) 18:28, 13 August 2020 (UTC)
 * this is the style explained, but IMO, it's not the best practice. it is better not to have this "p" thingy at all, and write like so: when using something like p={} at the top, and continuing to accumulate stuff to be exported all across the module, and eventually returning the obscure p, it is not at all clear what does this module exports, and requires hunting over the whole module trying to understand it. the module itself looks nicer and easier to review (and even modify) without   or   peppering the code. peace - קיפודנחש (talk) 23:12, 22 March 2021 (UTC)

Return statements
"If a return statement is reached, the block is exited and the values of the function call expression are those given by the return statement." In the example after this, is "return function( x )" a return statement? If it is, and the block is exited, it looks like the next line of the block "return x + n" is never used so is there a reason for it to be there? If it isn't a return statement, it should be explained somewhere; there is no other mention of "return function". Also in the "getting started" example after "return "Hello, world!"" if the block is exited what are "end" and "return p" for? Peter James (talk) 15:03, 12 August 2020 (UTC)
 * Yes, "return function( x )" is a return statement. However, instead of returning a string or integer or other simple value, the value it is returning is a function (definition), which itself has a return statement ("return x + n") inside it (note the relative indenting).
 * The functions available in a module are stored within an object, indexed by name (ie a table). In the "getting started" example, the object is  .  The function definition starts at the   keyword and ends at the   keyword. Defining a function does not execute it right away, it is just defined, and in this case the function definition is bound to the "hello" field of the   object.  The final "return p" returns the   object to the the lua/scribunto system, which uses the fields in that object to find the corresponding function when you pass in the name to the invoke template,  . --Clump (talk) 16:42, 12 August 2020 (UTC)

frame again
Hello, I cannot figure out where the mistake lies. My code begins as follows:

And I get permanent error «line 4: attempt to index local 'frame' (a nil value)». How am I supposed to access the args here? Lozman (talk) 21:05, 15 September 2020 (UTC)


 * @Lozman: You can use  only for functions called from wikitext. Such functions can access frame as the first (only) argument, but they must be added to the p variable (e.g.  ). Alternatively, you can access the frame object using.
 * (Note that your code needs  at the very end.) --Matěj Suchánek (talk) 09:52, 17 September 2020 (UTC)
 * Thanks a lot, that helped much. I think this behavior should be clearly documented, but I could not find it in the manual. Lozman (talk) 13:00, 17 September 2020 (UTC)

mw.text.encode parameter charset
About the documentation for #mw.text.encode. It says:
 * "charset ... should be a string as appropriate to go inside brackets in a Ustring pattern, i.e. the "set" in [set]. The default charset is "


 * 1. \-escape: The code string uses the backslash ("\") to escape character "'". Tests learned me that this escape method works also with other characters (writing in module namespace page), for example to include the backslash I add "\\" to the string; to success, other characters also could break the lua code. I think that this method be explicitly added to the description, because it is not clear and since it says "Ustring pattern", it implies that the escape character is "%" (being a pattern not regex).
 * 2. quote example: The text now says that the default input for  is " ", obviously including the outer ' '-quotes. It took some tests to find out they do not belong to the parameter input. Shouldn't they be outside of the code-formatted text then: "' '"?
 * I only think of this now: If this is to show the full input code (in module page, i.e., the quotes are Lua-required and not part of the input), it would be helpful to add the parameter too to the code.
 * 3. Sentence logic: Could the two full sentences be swapped? To reach: 1. This function changes these five characters; 2. Other character to encode, should be entered through parameter 2; they will be numerical.
 * 4. Use case: It would be helpful if for both encode and decode (which apply different default character sets?), a use case would be mentioned. XML? HTML subset?

Only #1 and #2 look like an incosistency to be corrected. -DePiep (talk) 17:55, 22 October 2020 (UTC)


 * 5. Is this consistent?
 * "Characters '<', '>', '&', '"', and the non-breaking space are replaced" (=5 characters)
 * "The default charset is ' '." (=6 characters, " " added).
 * (for clarity, we could write ' ' for '"', etc.). -DePiep (talk) 07:55, 23 October 2020 (UTC)

Fix
I just fixed the statement "which is unspecified, nil, or " ", returns a table" that seems to be untrue. Taylor 49 (talk) 16:39, 21 March 2021 (UTC)
 * More edits done. Taylor 49 (talk) 14:59, 22 March 2021 (UTC)

How to detect whether a category exists (page is created)?
frament:callParserFunction('#ifexist:sillypage','1','0')

works but is ugly and increases the cost. What is the best way to do? Taylor 49 (talk) 16:39, 21 March 2021 (UTC)
 * Hi ! Yup. But a category is just a page title, so you can take advantage exploring this: Extension:Scribunto/Lua reference manual and the  magic attribute :) Cheers! --Valerio Bozzolan (talk) 16:57, 21 March 2021 (UTC)

Proposal (?)
When used with the special value " " then the function returns a table which is good, but I lack a field: exists. I need to simplify my code, and more important reduce the cost. Calling "callParserFunction('#ifexist" and then " " gives the needed result but costs 2 bucks (expensive function counter increased by TWO). I would like to get both with a cost of ONE. Is there a chance to get such a field exists via Phabricator? Other ideas or thoughts around ? Taylor 49 (talk) 16:39, 21 March 2021 (UTC)


 * As explained above try  and   :) Cheers! --Valerio Bozzolan (talk) 16:59, 21 March 2021 (UTC)


 * Thanks ... will it cost ONE or TWO? Do I really have to create a title? I actually had explored the  but the idea to have to create a title looked less sane to me. Is there a way to reduce the cost? I need both the existence status and number of pages in the cat. Taylor 49 (talk) 17:04, 21 March 2021 (UTC)
 * Try ;) Spoiler: it's your lucky day! asd --Valerio Bozzolan (talk) 17:13, 21 March 2021 (UTC)
 * BTW creating a title is sane because you have literally a title, and you want to check if it exists. So yup, it's good :) --Valerio Bozzolan (talk) 17:14, 21 March 2021 (UTC)


 * I have tested both  and   (is there any relevant difference?) with same results (except swapped parameters):
 * it works
 * it is expensive
 * it crashes on the spot when the limit is reached (IIRC "callParserFunction('#ifexist" returned "false" but did not crash)
 * I have not yet tested my combo request about a category. It won't be today. Thanks again. Taylor 49 (talk) 20:34, 21 March 2021 (UTC)
 * Yup! Using the -stuff is the most efficient method. It's expensive because that category is not the current page, but trust me: it's less expensive than your previous way (calling parser function and parsing result). The page explodes if you request 500+ foreign information that has nothing to do with the current page. To handle the crash, use the   Lua structure. To avoid the crash, avoid to request 500+ foreign information (e.g. split the page in sub-pages). Difference between   and  : if you have a "Category:Stuff" string is better the first. If you have a "Stuff" category, is better the second. You can try to open a request to increase that limit (like this T160685) but usually WMF don't, to preserve resources. (This is what I know. Ambassador takes no pain. ihih). Cheers! --Valerio Bozzolan (talk) 09:18, 22 March 2021 (UTC)


 * Thanks. Sorry, but the lucky day does not work. It still costs 2 bucks (max 250 pages can be tested) to call -stuff and subsequently " ". The page worrying me is here: . Is there a chance to get the " " field for " " via phabricator? It is easy to create a bug/request, but I would like to avoid a " CLOSED:INVALID " due to missed obvious facts on my side. I have not yet tested   and  . Taylor 49 (talk) 14:55, 22 March 2021 (UTC)
 * Yup. Because "exists" does a lookup in the page table (first buck), while "pagesInCategory" does a lookup in the categorylinks table (second buck) so 2 bucks my friend. We can certainly propose alternative solutions (increase limits?; implement a method like   to preload the cache with 100 titles reducing DB communication running a query like   and increasing the expensive counter by a lower factor?; ...) but... actually to save your time I really suggest to split the page in two subpages, with fewer results per page. but don't expect to have this kind of stuff done before one year or two :D asd --Valerio Bozzolan (talk) 15:26, 22 March 2021 (UTC)


 * Thanks ... we must have misunderstood each other in some way and I had assumed that switching from  to   would reduce the cost from 2 bucks per cat to one but it doesn't. Maybe it saves at least some picoseconds of time or some picobits of memory. It obviously defeats the point of the proposal, if the 2 pieces of information have to be fetched from 2 separate tables both far away from Scribunto and far away from each other. I answered a related question far above (too good to be true).   works, but   is only pseudo-code, isn't it? But I have a another idea (Help:Extension:ParserFunctions):


 * For some use cases it is possible to emulate the ifexist effect with css, by using the selectors a.new (to select links to unexisting pages) or a:not(.new) (to select links to existing pages).


 * A page may have over 500 links and they are still blue or red ... never black or "inactivated". How can the parser get the right colour without fetching from the expensive table? If the fetching is "free" (as beer) when it comes to link colour, why isn't it free for "mw.title"? Taylor 49 (talk) 19:40, 23 March 2021 (UTC)
 * My friend, yours is a very smart question. --Valerio Bozzolan (talk) 14:06, 24 March 2021 (UTC)