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{{lua|Module:For loop}}
This template implements a [[for loop]] or a [[foreach loop]].

This template calls a user-specified template (the "called template") multiple times: once for each value in either 1) an iterated sequence or 2) an explicit list. Each value in the sequence or list is passed to the same specified parameter of the called template (the "variable parameter"). Optionally, pre- and postfixes can be attached to the passed values.

In addition to the specified variable parameter, other parameters of the called template ("static parameters") can be given a value which is the same in each iteration.

== Usage ==
{| class="wikitable"
! Group !! Parameter !! Meaning !! Default value
|-
! scope=row rowspan=3 | Mandatory
| '''1 (unnamed)''' || separator to output between calls (may be blank; whitespace is preserved) ||
|-
| '''call''' || template to call ||
|-
| '''pv''' || name (or number) of the variable parameter of the called template || style="text-align: center" | 1
|- style="border-top: 3px solid grey;"
! scope=row rowspan=3 | Option 1:<br/>iterated sequence
| '''start''' || first numeric value to pass to variable parameter || style="text-align: center" | 1
|-
| '''stop''' || maximum numeric value for variable parameter ||
|-
| '''by''' || iteration step size between values passed to variable parameter || style="text-align: center" | 1
|- style="border-top: 3px solid grey;"
! scope=row rowspan=2 | Option 2:<br/>explicit values
|  '''(unnamed parameters)''' || | explicit values, given as separate parameters (whitespace is stripped) ||
|-
| '''skipBlanks''' || set to "true" to skip empty parameter values || style="text-align: center" | false
|- style="border-top: 3px solid grey;"
! scope=row rowspan=5 | Other optional<br/>parameters
| '''pc[N]n''' || name (or number) of the Nth static parameter of the called template ||
|-
| '''pc[N]v''' || value for the Nth static parameter of the called template ||
|-
| '''prefix''' || static prefix prepended to each value passed to the variable parameter ||
|-
| '''postfix''' || static postfix appended to each value passed to the variable parameter ||
|- 
| '''substall''' || set to "false" to not substitute the called template when {{tl|for loop}} is substituted || style="text-align: center" | true
|}

''Either'' option 1 (iteration parameters) ''or'' option 2 (an explicit list of values) may be used, but not both.

The first unnamed parameter, prior to any explicit values, is a separator. The separator is a string that is output ''between'' calls to the template named in <code>|call=</code>. It is not output after the last call. 

=== Caution ===
*The separator can be prefixed with "1=", but in that case it cannot contain newlines and spaces at the start and end.
*If any parameter value contains an equals sign, use {{tlx|{{=}}}} (see [[Help:Template#Usage hints and workarounds|Template Usage hints and workarounds]]).
*If you use numbered parameters, note that the first value is parameter 2 (e.g. <code>|2=Your1stValue</code>), because parameter 1 is the separator.
*If you use numbered parameters, you must not skip any numbers. The loop will terminate after the first absent numbered parameter. (Parameters can be blank, but not absent.)

=== Substitution ===
The current Lua-based template supports [[WP:SUBST|substitution]]. If {{para|substall|no}} is not specified, then substituting the template will substitute everything, including the call to the template passed in {{para|call}}. If it is specified, then the template substitutes into a sequence of calls to the template specified.

Example: {{tlxs|for loop|sep |01|02|03|04|05|06|07|call{{=}}1x}} -> <code><nowiki>01sep 02sep 03sep 04sep 05sep 06sep 07</nowiki></code>, {{tlxs|for loop|sep |01|02|03|04|05|06|07|call={{1x}}|substall{{=}}no}} -> <code><nowiki>{{1x|01}}sep {{1x|02}}sep {{1x|03}}sep {{1x|04}}sep {{1x|05}}sep {{1x|06}}sep {{1x|07}}</nowiki></code>

For full substitution [[Special:ExpandTemplates]] can also be used.

== Examples ==
{| class="wikitable"
!Form
! style="width: 185px;" | Code
!Explanation
!Result
|-
! scope=row | Iterator
|
<syntaxhighlight lang="wikitext">{{for loop|&
 |call = spanbox
 |pv = font size
  |start=10
  |stop=52
  |by=8
 |postfix = px
 |pc1n = 1
 |pc1v = A
 |pc2n = background
 |pc2v = yellow
}}</syntaxhighlight>
| Call the template "spanbox" with values:
*font size = "[N]px", where N takes values starting with 10 and increasing by 8 while remaining less than or equal to 52
*1 (first unnamed parameter) = "A"
*background = "yellow"
Separating outputs with "&"
|{{for loop|&|call = spanbox
  |pv = font size
  |start=10|stop=52|by=8
  |postfix = px
  |pc1n = 1
  |pc1v = A
  |pc2n = background
  |pc2v = yellow
}}
|-
! scope=row | Explicit values
|<syntaxhighlight lang="wikitext">{{for loop|, |call=2x
|prefix=1
|00|01|02|03|04|05|06|07|08|09
|10|11|12|13|14|15|16|17|18|19
|20|21|22|23|24|25|26|27|28|29
|30|31|32|33|34|35|36|37|38|39
|40|41|42|43|44|45|46|47|48|49
|50|51|52|53|54|55|56|57|58|59
|60|61|62|63|64|65|66|67|68|69
|70|71|72|73|74|75|76|77|78|79
|80|81|82|83|84|85|86|87|88|89
|90|91|92|93|94|95|96|97|98|99
}}</syntaxhighlight>
| Call the template {{tl|2x}} (which just repeats its input twice) with values "1[NN]", where NN = "00" through "99" (given explicitly), separating the outputs with the string ", "
|{{for loop|, |call=2x
|prefix=1
|00|01|02|03|04|05|06|07|08|09
|10|11|12|13|14|15|16|17|18|19
|20|21|22|23|24|25|26|27|28|29
|30|31|32|33|34|35|36|37|38|39
|40|41|42|43|44|45|46|47|48|49
|50|51|52|53|54|55|56|57|58|59
|60|61|62|63|64|65|66|67|68|69
|70|71|72|73|74|75|76|77|78|79
|80|81|82|83|84|85|86|87|88|89
|90|91|92|93|94|95|96|97|98|99
}}
|-
! scope=row | Explicit values
|<syntaxhighlight lang="wikitext">{{for loop||call=tsh|skipBlanks=true|{{#switch:{{ROOTPAGENAME}}
|Namespace links=ln
|Article links=la
}}}} <!--Don't show {{tsh}} for |Lafd=lafd --></syntaxhighlight>
| {{t|for loop}} is useful for omitting a template call with one parameter being an inline expression that can be empty. It avoids repeating the parameter that the usual <code><nowiki>{{{1|}}} {{#if:{{{1|}}}|{{example|{{{1}}}}}}}</nowiki></code> does.
|{{for loop||call=tsh|skipBlanks=true|{{#switch:{{ROOTPAGENAME}}
|Namespace links=ln
|Article links=la
}}}} <!--Don't show {{tsh}} for |Lafd=lafd --> ({{t|for loop}} helped avoid the error message)
|}

=== Other examples with explicit values ===
<syntaxhighlight lang="wikitext">{{for loop|-|a|3||c|g|call=3x}}</syntaxhighlight> using {{tiw|3x}} gives

{{for loop|-|a|3||c|g|call=3x}}

<syntaxhighlight lang="wikitext">
{{for loop|

|a|3||c|g|call=3x}}
</syntaxhighlight> gives

{{for loop|

|a|3||c|g|call=3x}}

<syntaxhighlight lang="wikitext">
{|class="wikitable sortable"
!Test
|-
| {{for loop|
{{!}}-
{{!}} |a|b|c|d|e|call=3x}}
|}
</syntaxhighlight>

gives:

{|class="wikitable sortable"
!Test
|-
| {{for loop|
{{!}}-
{{!}} |a|b|c|d|e|call=3x}}
|}

<syntaxhighlight lang="wikitext">
{{for loop| |01|02|03|04|05|06|07|08|09|10|11|12|13|14|15|16|17|18|19
|20|21|22|23|24|25|26|27|28|29|30|31|32|33|34|35|36|37|38|39
|40|41|42|43|44|45|46|47|48|49|50|51|52|53|54|55|56|57|58|59
|60|61|62|63|64|65|66|67|68|69|70|71|72|73|74|75|76|77|78|79
|80|81|82|83|84|85|86|87|88|89|90|91|92|93|94|95|96|97|98|99
|100|101|102|103|104|105|106|107|108|109|110|111|112|113|114|115|116|117|118|119
|120|121|122|123|124|125|126|127|128|129|130|131|132|133|134|135|136|137|138|139
|140|141|142|143|144|145|146|147|148|149|150|151|152|153|154|call=1x}}
</syntaxhighlight>
gives:

{{for loop| |01|02|03|04|05|06|07|08|09|10|11|12|13|14|15|16|17|18|19
|20|21|22|23|24|25|26|27|28|29|30|31|32|33|34|35|36|37|38|39
|40|41|42|43|44|45|46|47|48|49|50|51|52|53|54|55|56|57|58|59
|60|61|62|63|64|65|66|67|68|69|70|71|72|73|74|75|76|77|78|79
|80|81|82|83|84|85|86|87|88|89|90|91|92|93|94|95|96|97|98|99
|100|101|102|103|104|105|106|107|108|109|110|111|112|113|114|115|116|117|118|119
|120|121|122|123|124|125|126|127|128|129|130|131|132|133|134|135|136|137|138|139
|140|141|142|143|144|145|146|147|148|149|150|151|152|153|154|call=1x}}

<syntaxhighlight lang="wikitext">
begin->{{for loop|{{=}} |01|02|03|04|05|06|07|08|09|10
|11{{=}}{{=}}{{=}}|12|13|14|15|16|17|18|19|call=1x}}<-end
</syntaxhighlight>
gives:

begin->{{for loop|{{=}} |01|02|03|04|05|06|07|08|09|10
|11{{=}}{{=}}{{=}}|12|13|14|15|16|17|18|19|call=1x}}<-end

== Notes about legacy code ==
This template is currently in its third incarnation. It now uses the [[WP:Lua|Lua]] code at [[Module:For loop]]. It was ported to Lua from [[mw:Help:Extension:ParserFunctions|ParserFunctions]]. There was also a previous version with a named "sep" parameter to specify the separator value. The template was originally based on [[m:Template:For|Template:For on meta]]. The template name was changed because there was already a [[Template:For|Template:For on Wikipedia]].

The old versions were limited to 150 variable values and four fixed parameters. There are no such limits in the current version. Also, in the first version the "sep" parameter didn't allow whitespace in the separator value. This was fixed with the second version and was retained in the current version.

== See also ==
*[[mw:Template:Fe]]
*[[mw:Template:foreach]]
*{{tim|tblb}}
*{{tiw|for nowiki}}
*{{tiw|item}}
*{{tiw|loop}}
*{{tiw|simple recursion}}
*[[Help:Parameter default]]
*[[Help:Array]]
*[[mw:Extension:LoopFunctions]]
*[[mw:Extension:Loops]]

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