Extension:Substitutor

The Substitutor extension allows to to do one-time string substitutions.

Description
Common parser functions and magic words in MediaWiki are parsed/displayed dynamically in MediaWiki. Sometimes this is not what you want. For example, you want a timestamp that is only evaluated the first time the page is saved and after that stay on that exact time. Or you want to generate a random ID that does not change with each page view.

This provides useful if you want to create unique names and URL's for "red links", or simply timestamp sites / changes.

Installation
Instead of downloading the zip archive you may also check this extension out via Git:

Usage
Use the tag, to define

The content of the tag will be parsed and replaced after you saved the article. The substitution will only happen exactly once - that's the whole point of this extension.

This extension is especially useful in combination with Extension:IDProvider.

Substitute vs. subst:
results in:

which is rendered as: