Parser function extensions

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A "parser function" is a template-like construct that returns a value based on at least one unnamed parameter, separated from the function name by a colon [:]. There may be more parameters, as well; like those of ordinary templates, these additional parameters are each preceded by a "pipe" [|]. In the case of a hash character [#] at the start of the function name (which prevents collision with namespaces and interwiki prefixes), this may or may not be considered part of the name. If it is considered part of the name, the syntax is of the form

{{functionname: argument 1 | argument 2 | argument 3...}}

If the caller has no arguments to provide the parser function, then the form is simply {{functionname:}} or, when a hash character applies (as is normally the case) then the form is {{#functionname:}}. If the trailing colon is not supplied, then functionname is not recognized by the parser.

Arguments cannot directly contain "|" or "}}" except as part of the code of a template call, parser function call, variable, link or image, but they can contain them arbitrarily using a template, e.g., m:Template:!, or a parser function.

The code can specify whether the function name is case-sensitive.

The separation of the arguments from each other is with "|", and from the function name is with the first ":" The expansion of each of these pieces is standard, as in Special:ExpandTemplates (which is a good place to experiment, by the way, if you are learning this stuff) and is beyond the control of the parser function itself.

However, everything else can be different for each parser function, including:

whether an argument is just a value, or of the form parname = parvalue, or whatever
if applicable, whether parameter names are case-sensitive

Syntax prescribed by a parser function extension

In view of the above, it is advantageous to make an extension such that the syntax to be used in an argument does not contain the pipe character "|" or double braces (more specifically, double closing braces "}}" ). This, in spite of the fact that a pipe character would otherwise seem a suitable symbol for, e.g., a choice or union (see, e.g., [1]). Allowing such codes is harmless if an alternative code is also allowed, e.g. "\" for "|".

Table of functions

extension	function	MediaWiki version
built-in	lc	1.7+
built-in	uc	1.7+
built-in	lcfirst	1.7+
built-in	ucfirst	1.7+
built-in	urlencode	1.7+
built-in	anchorencode	1.8+
built-in	localurl	1.7+
built-in	fullurl	1.7+
built-in	#language	1.7+
built-in	#special	1.9+
built-in	#tag	1.12+
ParserFunctions (usage)	#expr	1.19+
ParserFunctions (usage)	#ifexpr	1.19+
ParserFunctions (usage)	#if	1.19+
ParserFunctions (usage)	#ifeq	1.19+
ParserFunctions (usage)	#ifexist	1.19+
ParserFunctions (usage)	#rel2abs	1.19+
ParserFunctions (usage)	#titleparts	1.19+
ParserFunctions (usage)	#switch	1.19+
ParserFunctions (usage)	#time	1.19+
AddScriptCss	#addscript	Archived
Arrays	#arraydefine	1.23+
Arrays	#arraydiff	1.23+
Arrays	#arrayindex	1.23+
Arrays	#arrayintersect	1.23+
Arrays	#arraymerge	1.23+
Arrays	#arrayprint	1.23+
Arrays	#arrayreset	1.23+
Arrays	#arraysearch	1.23+
Arrays	#arraysearcharray	1.23+
Arrays	#arraysize	1.23+
Arrays	#arrayslice	1.23+
Arrays	#arraysort	1.23+
Arrays	#arraytohash	1.23+
Arrays	#arrayunion	1.23+
Arrays	#arrayunique	1.23+
Arrays	#hashtoarray	1.23+
Attachments	#attach	1.31+
Attachments	#exturl	1.31+
Babel	#babel	1.30+
CSS	#css	1.25+
Coordinate	#coordinate	Archived
Counter	#+	1.15+
Data	#data	Archived
Data	#sort	Archived
DynamicFunctions	#arg	Archived
DynamicFunctions	#ip	Archived
DynamicFunctions	#rand	Archived
DynamicFunctions	#skin	Archived
DynamicPageList (third-party)	#dpl	Archived
DynamicPageList3	#dpl	1.39+
ExpandAfter	#expandafter (deprecated, see: #tag)	Archived
ForeachFunction	#foreachx	Archived
ForeachFunction	#foreachy	Archived
HasCategory	#ifhascat	Archived
HideNamespace	#hidens	Archived
HideNamespace	#unhidens	Archived
ImageLink	#img (old: #imagelink, deprecated)	Archived
Infobox Data Capture	#dataentry	Archived
Infobox Data Capture	#listsplit	Archived
InterWikiLinkManager	#iwl	Archived
KeyValue	#keyvalue	Archived
Labeled Section Transclusion	#lst	1.25+
Labeled Section Transclusion	#lstx	1.25+
Labeled Section Transclusion	#lsth	1.25+
LoopFunctions	#for	1.23+
LoopFunctions	#foreach	1.25+
Loops	#while	1.25+
Loops	#dowhile	1.25+
Loops	#forargs	1.25+
Loops	#fornumargs	1.25+
Loops	#loop	1.25+
Maps	#geocode	1.27+
Maps	#display_map	1.27+
Maps	#display_point	1.27+
Maps	#coordinates	1.27+
Maps	#distance	1.27+
MediaFunctions	#media..	1.23+
PageAfterAndBefore	#pagebefore	Archived
PageAfterAndBefore	#pageafter	Archived
PageAfterAndBefore	#firstpage	Archived
PageAfterAndBefore	#lastpage	Archived
PageFunctions	#pagetitle	Archived
PageFunctions	#pagesubtitle	Archived
PageFunctions	#pageexists	Archived
PageFunctions	#varset	Archived
PageFunctions	#varget	Archived
PageFunctions	#varcapset	Archived
PageFunctions	#cshow	Archived
PageFunctions	#varaset	Archived
PageFunctions	#varaget	Archived
ParserFunctions (extended)	#expr (extended)	Archived
ParserFunctions (extended)	#ifexpr (extended)	Archived
ParserFunctions (extended)	#min	Archived
ParserFunctions (extended)	#max	Archived
ParserFunctions (extended)	#if	Archived
ParserFunctions (extended)	#ifeq	Archived
ParserFunctions (extended)	#ifexist	Archived
ParserFunctions (extended)	#rel2abs	Archived
ParserFunctions (extended)	#switch	Archived
ParserFunctions (extended)	#time	Archived
Pipe Escape	#!	1.23+
QPoll	#qpuserchoice	Archived
RegexTools	#regex	Archived
RegexTools	#regex_vars	Archived
SecureProperties	#pg	Archived
SecureProperties	#ps	Archived
SecureProperties	#pf	Archived
SecureProperties	#gg	Archived
SecureProperties	#gs	Archived
Semantic MediaWiki	#ask	1.27+
Semantic MediaWiki	#concept	1.27+
Semantic MediaWiki	#info	1.27+
Semantic MediaWiki	#show	1.27+
Semantic MediaWiki	#set	1.27+
StringFunctions	#len	1.7+
StringFunctions	#pos	1.7+
StringFunctions	#rpos	1.7+
StringFunctions	#sub	1.7+
StringFunctions	#pad	1.7+
StringFunctions	#replace	1.7+
StringFunctions	#explode	1.7+
StringFunctions	#urlencode	1.7+
StringFunctions	#urldecode	1.7+
TreeAndMenu	#tree	1.23+
TreeAndMenu	#menu	1.23+
Variables	#vardefine	1.29+
Variables	#vardefineecho	1.29+
Variables	#var	1.29+
Variables	#varexists	1.29+
Variables	#var_final	1.29+
Wikibase Client	#property
Wikibase Client	#statements

Syntax prescribed by a parser function extension

Table of functions

See also