Template:Ifsubst/doc

This is a documentation subpage for Template:Ifsubst.
It contains usage information, categories and other content that is not part of the original template page.

This template is used in MediaWiki:Abusefilter-disallowed-semicolon, and on approximately 54,000 pages.
Changes to it can cause immediate changes to the Wikipedia user interface.
To avoid major disruption, any changes should be tested in the template's /sandbox or /testcases subpages, or in your own user subpage. The tested changes can be added to this page in a single edit. Please discuss changes on the talk page before implementing them.

Usage

Meta template that returns the first parameter if evaluated during substitution, and the second parameter if evaluated during transclusion.
Note that this template must be used in safesubst mode to work properly:

{{ safesubst:<noinclude/>ifsubst| yes | no }}

The |demo= parameter can be used for testing the template. Set |demo=yes to always display the yes text, |demo=no to always display the no text, or |demo={{{demo|}}} to pass through the value from the parent template.

List of subst helper templates

{{require substitution}} – Prints an error unless substituted.
- {{always substitute}} – For the doc of the above templates; prints a message asking for it be substituted.
- {{never substitute}} – The reverse of {{always substitute}}. For the doc of templates which should not be substituted; prints a message asking for it not to be substituted.
- {{substitution}} – Allows free-fill description of whether the template should be substituted and under what conditions.
{{ifsubst}} – Forks if substituted or not.
{{issubst}} – Returns "yes" if substituted.
Module:Unsubst – Prevents substitution.
Module:Unsubst-infobox – Prevents substitution for infoboxes, cleans up parameters.