Help:Parser function
Template:H:h A "colon function" is a predefined template with one parameter, or in other words, a variable with a parameter. The parameter is unnamed and separated from the function name by the symbol ":", unlike regular templates, which use "|".
Thus the syntax is:
- {{ function name : parameter value }}
The function name is not case-sensitive.
Formatting
LC
Makes a text lowercase.
{{lc:AbCdEf}} gives abcdef.
{{lc:Ä Β Ç}} gives ä β ç, expected ä β ç.
UC
Makes a text uppercase.
{{uc:AbCdEf}} gives ABCDEF.
{{uc:ä β ß}} gives Ä Β SS, expected: Ä Β SS. Don't expect too much.
LCFIRST
Makes the first character lowercase: {{lcfirst:Ab Cd}} gives ab Cd.
UCFIRST
Makes the first character uppercase: {{ucfirst:aB cD}} gives AB cD.
NS
Gives the namespace name for a given namespace number or name:
{{ns:4}} gives Wikipedia.
{{ns:{{ns:12}}_talk}} gives Help talk.
{{ns:project}} gives Wikipedia.
However {{ns:{{SITENAME}}}} for {{SITENAME}}=Wikipedia doesn't work, on Meta it has the same effect as {{Meta}}, calling an existing Template:Meta.
Similarly {{ns:{{ns:8}} talk}} fails without underscore: MediaWiki talk. See Help:Variable for more canonical names like "project" and "talk".
NS:1
{{ns:{{ns:0}}_talk}} fails: Talk. The canonical name for the talk namespace of articles is "talk" and not "_talk". But the following constructs work:
{{ns:01}} gives Talk,
{{ns:+1}} gives Talk,
{{ns:TALK}} gives Talk, and
{{ns:{{ns:1}}}} gives also Talk. Space sensitive, but not case sensitive.
NS:0
'''#{{ns:0}}#''' gives ##, an empty string. This is often handy, less vulnerable than a template void or similar,
and less cryptic than magic words like __END__.
In constructs like {{ {{#if: {{{T|}}} | {{{T}}} | ns:0}} }}, where parameter T is
normally the name of a template to be evaluated, but can be undefined or empty, {{ns:0}}
is then a clean empty string. Without it {{}} would result in {{}}.
Please note that {{ns:{{ns:0}}}} fails: . NS cannot handle an empty {{ns:0}} argument.
Empty section title
An empty section title like above is obtained using, in this case, ==== {{ns:0}} ====. This is dubious, but arguably better than using the same trick to get invisble section headers twice on a page. At least /* {{ns:0}} */ makes sense in the edit history, if there's only one section using this particular trick.
As shown in the table of contents this and similar tricks result in non-functional links. In conjunction with __NOTOC__ it's less harmful, and maybe useful to get edit links for invisible sections with categories and interlanguage links. Other possibilities for different invisible section headers:
=== __NOTOC__ ====== ====== ======   ===
#expr
Parser function #expr converts a string containing a numeric or boolean expression into its value. See also Help:Calculation.
Parameter expression
The parameter value can be an expression involving (possibly multilevel): concatenation, applying a template, parser function, or colon function, or using a variable.
Examples:
- using m:Template:tc (backlinks edit), {{uc:{{tc}}}} gives IN.
- using m:Template:x3 (backlinks edit), {{#expr:{{x3|1}}/3}} gives 37
Substitution
- See also: Help:Substitution.
Applying "subst:" to a colon function works:
{{subst:LC:AbC}} gives abc.
Note that unless a technique like optional recursive substitution
is used, substituting a template which uses a colon function does not replace that colon function with its result.
See also