Extension:WhiteSpace

The WhiteSpace extension provides two tags to control whitespace in templates: discards itself and all whitespace (including newlines) after the tag,  replaces itself with a newline.

Rationale
In wikitext spaces and newlines do matter. Leading space causes a paragraph to be verbatim, newline terminates a list item, etc. This means that template code cannot be formatted freely. For example, two subsequent template calls:

being reformatted as:

may produce different result (e. g. two list items instead of one). This is not a big deal for a simple template, but it quickly become a real issue for complicated templates. Let us consider a real example, a small part of Template:Extension:

HTML comments allows splitting template code to lines but it pollutes template code so the overall result is not so good. Using  the code can be reformatted as:

Of course, it is just another style of formatting, but  allows using this style regularly and uniformly.

Download
git clone https://gerrit.wikimedia.org/r/mediawiki/extensions/WhiteSpace.git

Installation
Note: This extension requires patching MediaWiki core. The one-line patch introduces a parser hook which makes implementation of this extension possible. See Requests for comment/New hook: ParserBeforePreprocess for rationale.

In the MediaWiki root directory:

$ patch -p0 -i extensions/WhiteSpace/MediaWiki-1.18.1.patch

The add to your `':

require_once( "$IP/extensions/WhiteSpace/WhiteSpace.php" );

Installing on MediaWiki v1.25 or newer
The `wfRunHooks` function has been deprecated since v1.25, so the MediaWiki-1.18.1.patch patch file will not work and you will see a "Fatal Error" or "ParseError".

Instead, manually edit MediaWiki core file `includes/parser/Parser.php`. Find function `preprocessToDom` (around line 2952) and add this as the first line in that function:

Hooks::run( 'ParserBeforePreprocess', array( $this, &$text, $flags ) );

Known issues

 * Patching the MediaWiki core required. :-(