Help:Template

This page is about designing templates more than using them. For details of how to use existing templates, see Help:Editing or the documentation for any template.

Including

To include a template---or any page---in another page:

{{T}} includes Template:T
{{:Page name}} includes Page name
{{subst:T}} or {{subst::Page name}} are instead replaced by the current contents of Template:T or Page name
{{msgnw:T}} includes Template:T in <nowiki> style

If-templates

Templates have a limited condition-testing functionality. The following are based on code from the MediaWiki manuals:

{{Ifn|value|result}}: Yields result if value isn't blank. (Compare shell's if [ -n "value" ]; then result; fi) One limitation: {{ifn|2=result}} yields result (but works properly if value is defined and empty).
{{Ifz|value|result}}: Yields result if value is blank. (Compare shell's if [ -z "value" ]; then result; fi)
{{If|value|resultyes|resultno}}: Yields resultyes if value isn't blank; otherwise it yields resultno. (Compare shell's if [ -n "value"]; then resultyes; else resultno; fi) One limitation: {{if|2=resultyes}} yields resultyes (but works properly if value is defined and empty, or resultno is defined).
{{Ifeq|value|test|resultyes|resultno}}: Yields resultyes if value equals test; otherwise it yields resultno. (Compare shell's if ["value" = test ]; then resultyes; else resultno; fi)

Now that we've upgraded to MediaWiki >= 1.19.1, though (currently at 1.21.1), we should be able to use {{#if:value|result|resultno}} and {{#ifeq:value|test|resultyes|resultno}}, which don't suffer the above limitations. Here are more details. When I try these, though, I find that they still don't work. Maybe these parser function hooks would need to be explicitly enabled.

Template arguments

In the template's expansion markup, {{{1}}} will expand to the first (implicitly named) argument, and {{{2|default}}} will expand to the second but default to default if the second argument is not supplied. Note that if the template is invoked as {{Foo|arg1|}}, then the second argument has been supplied; here it's the empty string.

Arguments can also be explicitly named/numbered, as when you invoke {{Foo|bar=arg1|2=}}. Arguments supplied in these ways have leading and trailing whitespace trimmed. (Whitespace is preserved when arguments are only implicitly named.)

To suppress expansion of an argument's contents, wrap {{{argument}}} with {{#tag:nowiki|...}}; see Template:Cat for an example.

Inside a template's expansion markup, substrings beginning with *, #, :, or ; are automatically prefixed by a newline. Use start{{{dummy|;}}}finish to generate start;finish. (The empty string may be used for dummy.)

{{ns:0}} expands to the empty string.

If your template arguments are unexpectedly expanding as {{{1}}}, then you neglected to supply the argument; or you supplied text that the wiki markup engine is interpreting in a way you didn't expect. You can stop this from happening by surrounding the relevant text with <nowiki> tags. For example, instead of:

{{Cmd|export PS1="(chroot)$PS1"}}

use:

{{Cmd|<nowiki>export PS1="(chroot)$PS1"</nowiki>}}

A shorter alternative is to explicitly name the first argument:

{{Cmd|1=export PS1="(chroot)$PS1}"}}

See also the escape characters for {{Cat}}, which can be used inside any template invocation.

Skeleton for a new template

<noinclude>{{Template}}
Short description.

=== Usage ===
Longer description.

<pre>{{Foo|arg}}</pre>

Further comments.

=== Example ===

<pre>{{Foo|arg}}</pre>

will produce:
{{Foo|arg}}

=== See also ===

* [[:Template:Bar]]

</noinclude><includeonly>EXPANSION</includeonly>