View source for Module:Params/doc

{{Module rating|beta}}
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The <code><nowiki>{{#invoke:params}}</nowiki></code> module is designed to be adopted by those templates that want to have a deep control of their parameters. It is particularly useful to [[variadic template]]s, to which it offers the possibility to count, list, map and propagate the parameters received without knowing their number in advance.

The module offers elegant shortcuts to non variadic templates as well. Outside templates it has virtually no applications; hence, if you plan to make experiments, make sure to do them from within a template, or you will not be able to see much.

In case your template uses this module, please add {{tji|lua|Module&#58;Params}} to its the documentation page, so that if breaking changes will be introduced in the future the template will be easily traceable.

== General usage ==
Among the possibilities that the module offers there is that of performing a series of actions after novel arguments have been concatenated to a template's incoming parameters. As this makes it necessary to keep the argument slots clean from interferences, instead of named arguments in order to specify options this module uses ''piping functions'' (i.e. functions that expect to be [[Pipeline (software)|piped]] instead of returning to the caller), or ''modifiers''. This creates a syntax similar to the following example:

<syntaxhighlight lang="wikitext">{{#invoke:params|[modifier]|[...]|[modifier]|[...]|function|[...]}}</syntaxhighlight>

For instance, as the name suggests, the <code>[[#list|list]]</code> function lists the parameters wherewith a template was called. By default it does not add delimiters, but returns an indistinct blob of text in which keys and values are sticked to each other. However, by using the <code>[[#setting|setting]]</code> modifier, we are able to declare a key-value delimiter (<code>p</code>) and an iteration delimiter (<code>i</code>). And so, if we imagined a template named <code><nowiki>{{Example template}}</nowiki></code> containing the following wikitext,

<syntaxhighlight lang="wikitext">{{#invoke:params|setting|i/p|<br />|: |list}}</syntaxhighlight>

and such template were called with the following arguments,

{{tj|Example template|Beast of Bodmin: A large feline inhabiting Bodmin Moor
  |Morgawr: A sea serpent|Owlman: A giant owl-like creature}}

the following result would be produced:

: Owlman: A giant owl-like creature<br />Beast of Bodmin: A large feline inhabiting Bodmin Moor<br />Morgawr: A sea serpent

We can also do more sophisticated things; for instance, by exploiting the possibility to set a header (<code>h</code>) and a footer (<code>f</code>), we can transform the previous code into a generator of [https://html.spec.whatwg.org/multipage/grouping-content.html#the-dl-element definition lists],

<syntaxhighlight lang="wikitext">{{#invoke:params|setting|h/p/i/f|<dl><dt>|</dt><dd>|</dd><dt>|</dd></dl>|list}}</syntaxhighlight>

thus yielding:

:; Beast of Bodmin
:: A large feline inhabiting Bodmin Moor
:; Morgawr
:: A sea serpent
:; Owlman
:: A giant owl-like creature

By placing the <code>[[#with_name_matching|with_name_matching]]</code> modifier before the <code>[[#list|list]]</code> function we will be able to filter some parameters out – such as, for instance, all parameter names that do not end with an “n”:

<syntaxhighlight lang="wikitext">{{#invoke:params|with_name_matching|n$|setting|h/p/i/f|<dl><dt>|</dt><dd>|</dd><dt>|</dd></dl>|list}}</syntaxhighlight>

Thus, the previous code will produce:

:; Beast of Bodmin
:: A large feline inhabiting Bodmin Moor
:; Owlman
:: A giant owl-like creature

This mechanism has the intrinsic advantage that it allows to concatenate infinite modifiers. And so, in order to get the accurate result that we want to obtain we could write:

<syntaxhighlight lang="wikitext">{{#invoke:params|non-sequential|with_name_matching|^B|with_name_matching|n$|with_value_matching|feline|setting|h/p/i/f|<dl><dt>|</dt><dd>|</dd><dt>|</dd></dl>|list}}</syntaxhighlight>

The two modifiers <code>[[#sequential|sequential]]</code> and <code>[[#non-sequential|non-sequential]]</code> refer to a technical jargon used in wikitext: given a parameter list, the subgroup of sequential parameters is constituted by the largest group of consecutive numerical parameters starting from {{tjp|1:}} – this is known as the parameters' “sequence”. A parameter list that does not have a first parameter specified does not possess a sequence.

== Functions ==

Here follows the list of functions. You might want to see also [[#Modifiers (piping functions)|§ Modifiers]].

{{vpad}}

=== <code>count</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>count</code>
| label1 = Num. of arguments | data1 = 0
| label2 = Often preceeded by | data2 = <code>[[#sequential|sequential]]</code>
| label3 = Not affected by | data3 = <code>[[#all_sorted|all_sorted]]</code>
| header4 =  See also
| data5 = {{mlx|ParameterCount|}}
}}

; Brief
: ''Count the number of parameters wherewith a template was called''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|count}}</syntaxhighlight>

This function does not take arguments.

{{vpad|1.5em}}

=== <code>concat_and_call</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>concat_and_call</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = Not affected by | data2 = <code>[[#all_sorted|all_sorted]]</code>
| header3 =  See also
| data4 = <code>[[#concat_and_invoke|concat_and_invoke]]</code>
}}

; Brief
: ''Prepend numerical arguments to the current parameters or impose non-numerical arguments, then propagate everything to a custom template''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|concat_and_call|template name|[prepend 1]|[prepend 2]|[...]|[prepend n]|[named item 1=value 1]|[...]|[named item n=value n]|[...]}}</syntaxhighlight>

For example, if our <code><nowiki>{{Example template}}</nowiki></code> had the following code,

<syntaxhighlight lang="wikitext">{{#invoke:params|concat_and_call|foo bar|elbow|earth|room|7=classy|hello=not today}}</syntaxhighlight>

and were called with,

{{tj|Example template|one|two|three|hello: world|wind: spicy}}

the following call to the <code><nowiki>{{Foo bar}}</nowiki></code> template would be performed:

{{tj|Foo bar|elbow|earth|room|7: classy|8: one|9: two|10: three
  |wind: spicy|hello: not today}}

If no other argument besides the template name are provided this function simply echoes the current parameters to another template.

{{vpad}}

{{A note}} All arguments passed to this function except the template name are not trimmed of their leading and trailing spaces. The <code>concat_and_call</code> function name itself, however, will be trimmed of its surrounding spaces.

{{vpad|1.5em}}

=== <code>concat_and_invoke</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>concat_and_invoke</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = Not affected by | data2 = <code>[[#all_sorted|all_sorted]]</code>
| header3 =  See also
| data4 = <code>[[#concat_and_call|concat_and_call]]</code>
}}

; Brief
: ''Prepend numerical arguments to the current parameters, or impose non-numerical arguments; then propagate everything to a custom module''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|concat_and_invoke|module name|function name|[prepend 1]|[prepend 2]|[...]|[prepend n]|[named item 1=value 1]|[...]|[named item n=value n]|[...]}}</syntaxhighlight>

Exactly like <code>[[#concat_and_call|concat_and_call]]</code>, but invokes a module instead of calling a template.

{{vpad}}

{{A note}} All arguments passed to this function except the module name and the function name are not trimmed of their leading and trailing spaces. The <code>concat_and_invoke</code> function name itself, however, will be trimmed of its surrounding spaces.

{{vpad|1.5em}}

=== <code>value_of</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>value_of</code>
| label1 = Num. of arguments | data1 = 1
| label2 = Relevant [[#setting|runtime variables]] | data2 = <code>h</code>, <code>f</code>, <code>n</code>
| label3 = Not affected by | data3 = <code>[[#all_sorted|all_sorted]]</code>
| header4 =  See also
| data5 = <code>[[#list_values|list_values]]</code>
}}

; Brief
: ''Get the value of a single parameter''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|value_of|parameter name}}</syntaxhighlight>

Without modifiers this function is similar to writing <syntaxhighlight lang="wikitext" inline>{{{parameter name|}}}</syntaxhighlight>. With modifiers, however, it allows to reach parameters that would be unreachable without knowing their number in advance. For instance, writing

<syntaxhighlight lang="wikitext">{{#invoke:params|cutting|-2|0|value_of|1}}</syntaxhighlight>

will expand to the value of the second-last sequential parameter, independently of how many parameters the template was called with. If no matching parameter is found this function expands to nothing. A header (<code>h</code>), a footer (<code>f</code>), and a fallback text (<code>n</code>) can be declared via the <code>[[#setting|setting]]</code> modifier – the strings assigned to the key-value pair delimiter (<code>p</code>) and the iteration delimiter (<code>i</code>) will be ignored.

{{vpad|1.5em}}

=== <code>list</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>list</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = [[#sequential|Sortable]] | data2 = Yes
| label3 = Relevant [[#setting|runtime variables]] | data3 = <code>h</code>, <code>p</code>, <code>i</code>, <code>f</code>, <code>n</code>
| header4 =  See also
| data5 = <code>[[#list_values|list_values]]</code>
}}

; Brief
: ''List the template parameters (both their names and their values)''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|list}}</syntaxhighlight>

This function does not take arguments.

If the <code>[[#setting|setting]]</code> modifier was not placed earlier, this function will not add delimiters, but will return an indistinct blob of text in which keys and values are sticked to each other. A header (<code>h</code>), a key-value pair delimiter (<code>p</code>), an iteration delimiter (<code>i</code>), a footer (<code>f</code>), and a fallback text (<code>n</code>) can be declared via <code>[[#setting|setting]]</code>.

For example, the following code

<syntaxhighlight lang="wikitext">{{#invoke:params|setting|h/i/p/f/n|'''Parameters passed:''' |); | (|)|'''No parameters were passed'''|list}}</syntaxhighlight>

will generate an output similar to the following.

: '''Parameters passed:''' Owlman (A giant owl-like creature); Beast of Bodmin (A large feline inhabiting Bodmin Moor); Morgawr (A sea serpent)

{{vpad|1.5em}}

=== <code>list_values</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>list_values</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = [[#sequential|Sortable]] | data2 = Yes
| label3 = Often preceeded by | data3 = <code>[[#sequential|sequential]]</code>
| label4 = Relevant [[#setting|runtime variables]] | data4 = <code>h</code>, <code>i</code>, <code>f</code>, <code>n</code>
| header5 =  See also
| data6 = <code>[[#list|list]]</code>, <code>[[#value_of|value_of]]</code>, {{mlx|separated entries|}}
}}

; Brief
: ''List the values of the incoming parameters''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|list_values}}</syntaxhighlight>

This function does not take arguments.

The <code>[[#sequential|sequential]]</code> modifier normally accompanies this function. If the <code>[[#setting|setting]]</code> modifier was not placed earlier, this function will not add delimiters, but will return an indistinct blob of text in which values are sticked to each other. A header (<code>h</code>), an iteration delimiter (<code>i</code>), a footer (<code>f</code>), and a fallback text (<code>n</code>) can be declared via <code>[[#setting|setting]]</code> – the string assigned to the key-value pair delimiter (<code>p</code>) will be ignored.

For example, the following code

<syntaxhighlight lang="wikitext">{{#invoke:params|setting|h/i/p/f/n|'''Parameters passed:''' |); | (|)|'''No parameters were passed'''|list_values}}</syntaxhighlight>

will generate an output similar to the following.

: '''Values of parameters passed:''' A giant owl-like creature; A large feline inhabiting Bodmin Moor; A sea serpent.

{{vpad|1.5em}}

=== <code>call_for_each</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>call_for_each</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = [[#sequential|Sortable]] | data2 = Yes
| label3 = Relevant [[#setting|runtime variables]] | data3 = <code>h</code>, <code>i</code>, <code>f</code>, <code>n</code>
| header4 =  See also
| data5 = <code>[[#call_for_each_value|call_for_each_value]]</code>, <code>[[#invoke_for_each|invoke_for_each]]</code>, <code>[[#magic_for_each|magic_for_each]]</code>, {{mlx|for loop|}}, {{tl2|for loop}}
}}

; Brief
: ''For each parameter passed to the caller template, call a custom template with at least two parameters (key and value)''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|call_for_each|template name|[append 1]|[append 2]|[...]|[append n]|[named param 1=value 1]|[...]|[named param n=value n]|[...]
}}</syntaxhighlight>

All unnamed parameters following the template name will be placed after the key-value pair. Named parameters will be passed verbatim. A header (<code>h</code>), an iteration delimiter (<code>i</code>), a footer (<code>f</code>), and a fallback text (<code>n</code>) can be declared via the <code>[[#setting|setting]]</code> modifier – the string assigned to the key-value pair delimiter (<code>p</code>) will be ignored.

Calling a template for each key-value pair with

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|call_for_each|foobar}}</syntaxhighlight>

will be different than writing

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|for_each|{{foobar|$#|$@}}}}</syntaxhighlight>

In the first example each key-value pair will be passed to the {{tl|foobar}} template, while in the second example the <code>$#</code> and <code>$@</code> tokens will be expanded ''after'' the {{tl|foobar}} template has been called. In most cases this will make no difference, however there are several situations where it will lead to nonsensical results.

{{vpad}}

{{A note}} All arguments passed to this function except the template name are not trimmed of their leading and trailing spaces. The <code>call_for_each</code> function name itself, however, will be trimmed of its surrounding spaces.

{{vpad|1.5em}}

=== <code>invoke_for_each</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>invoke_for_each</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = [[#sequential|Sortable]] | data2 = Yes
| label3 = Relevant [[#setting|runtime variables]] | data3 = <code>h</code>, <code>i</code>, <code>f</code>, <code>n</code>
| header4 =  See also
| data5 = <code>[[#invoke_for_each_value|invoke_for_each_value]]</code>, <code>[[#call_for_each|call_for_each]]</code>, <code>[[#magic_for_each|magic_for_each]]</code>
}}

; Brief
: ''For each parameter passed to the caller template, invoke a custom module function with at least two arguments (key and value)''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|invoke_for_each|module name|module function|[append 1]|[append 2]|[...]|[append n]|[named param 1=value 1]|[...]|[named param n=value n]|[...]}}</syntaxhighlight>

Exactly like <code>[[#call_for_each|call_for_each]]</code>, but invokes a module instead of calling a template.

Invoking a module function for each key-value pair with

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|invoke_for_each|foobar|main}}</syntaxhighlight>

will be different than writing

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|for_each|{{#invoke:foobar|main|$#|$@}}}}</syntaxhighlight>

In the first example each key-value pair will be passed to the {{ml|foobar|main}} module function, while in the second example the <code>$#</code> and <code>$@</code> tokens will be expanded ''after'' the module function has been invoked. There might be cases in which this will make no difference, however there are several situations where it will lead to nonsensical results.

{{vpad}}

{{A note}} All arguments passed to this function except the module name and the function name are not trimmed of their leading and trailing spaces. The <code>invoke_for_each</code> function name itself, however, will be trimmed of its surrounding spaces.

{{vpad|1.5em}}

=== <code>magic_for_each</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>magic_for_each</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = [[#sequential|Sortable]] | data2 = Yes
| label3 = Relevant [[#setting|runtime variables]] | data3 = <code>h</code>, <code>i</code>, <code>f</code>, <code>n</code>
| header4 =  See also
| data5 = <code>[[#magic_for_each_value|magic_for_each_value]]</code>, <code>[[#call_for_each|call_for_each]]</code>, <code>[[#invoke_for_each|invoke_for_each]]</code>
}}

; Brief
: ''For each parameter passed to the caller template, call a magic word with at least two arguments (key and value)''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|magic_for_each|parser function|[append 1]|[append 2]|[...]|[append n]|[named param 1=value 1]|[...]|[named param n=value n]|[...]}}</syntaxhighlight>

Exactly like <code>[[#call_for_each|call_for_each]]</code>, but calls a [[:mw:Help:Magic words#Parser functions|parser function]] instead of a template.

{{vpad}}

{{A note}} All arguments passed to this function except the magic word are not trimmed of their leading and trailing spaces. The <code>magic_for_each</code> function name itself, however, will be trimmed of its surrounding spaces.

{{vpad|1.5em}}

=== <code>call_for_each_value</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>call_for_each_value</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = [[#sequential|Sortable]] | data2 = Yes
| label3 = Often preceeded by | data3 = <code>[[#sequential|sequential]]</code>
| label4 = Relevant [[#setting|runtime variables]] | data4 = <code>h</code>, <code>i</code>, <code>f</code>, <code>n</code>
| header5 =  See also
| data6 = <code>[[#call_for_each|call_for_each]]</code>, <code>[[#invoke_for_each_value|invoke_for_each_value]]</code>, <code>[[#magic_for_each_value|magic_for_each_value]]</code>, {{mlx|for loop|}}, {{tl2|for loop}}
}}

; Brief
: ''For each parameter passed to the caller template, call a custom template with at least one parameter (i.e. the parameter's value)''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|call_for_each_value|template name|[append 1]|[append 2]|[...]|[append n]|[named param 1=value 1]|[...]|[named param n=value n]|[...]}}</syntaxhighlight>

The <code>[[#sequential|sequential]]</code> modifier normally accompanies this function. All unnamed parameters following the template name will be appended after the value parameter. Named parameters will be passed verbatim. A header (<code>h</code>), an iteration delimiter (<code>i</code>), a footer (<code>f</code>), and a fallback text (<code>n</code>) can be declared via the <code>[[#setting|setting]]</code> modifier – the string assigned to the key-value pair delimiter (<code>p</code>) will be ignored.

For example, calling {{tl|tl}} with each parameter can be done by writing

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|setting|i|, |call_for_each_value|tl}}</syntaxhighlight>

This will be different than writing

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|setting|i|, |for_each|{{tl|$@}}}}</syntaxhighlight>

In the first example each value will be passed to the {{tl|tl}} template, while in the second example the <code>$@</code> token will be expanded ''after'' the {{tl|tl}} template has been called. Here this will make no difference, however there are several situations where it will lead to nonsensical results.

{{vpad}}

{{A note}} All arguments passed to this function except the template name are not trimmed of their leading and trailing spaces. The <code>call_for_each_value</code> function name itself, however, will be trimmed of its surrounding spaces.

{{vpad|1.5em}}

=== <code>invoke_for_each_value</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>invoke_for_each_value</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = [[#sequential|Sortable]] | data2 = Yes
| label3 = Often preceeded by | data3 = <code>[[#sequential|sequential]]</code>
| label4 = Relevant [[#setting|runtime variables]] | data4 = <code>h</code>, <code>i</code>, <code>f</code>, <code>n</code>
| header5 =  See also
| data6 = <code>[[#call_for_each_value|call_for_each_value]]</code>, <code>[[#invoke_for_each|invoke_for_each]]</code>, <code>[[#magic_for_each_value|magic_for_each_value]]</code>
}}

; Brief
: ''For each parameter passed to the caller template, invoke a custom module function with at least one argument (i.e. the parameter's value)''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|invoke_for_each_value|module name|module function|[append 1]|[append 2]|[...]|[append n]|[named param 1=value 1]|[...]|[named param n=value n]|[...]}}</syntaxhighlight>

Exactly like <code>[[#call_for_each_value|call_for_each_value]]</code>, but invokes a module instead of calling a template.

Invoking a module function for each value with

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|invoke_for_each_value|foobar|main}}</syntaxhighlight>

will be different than writing

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|for_each|{{#invoke:foobar|main|$@}}}}</syntaxhighlight>

In the first example each value will be passed to the {{ml|foobar|main}} module function, while in the second example the <code>$@</code> token will be expanded ''after'' the module function has been invoked. There might be cases in which this will make no difference, however there are several situations where it will lead to nonsensical results.

{{vpad}}

{{A note}} All arguments passed to this function except the module name and the function name are not trimmed of their leading and trailing spaces. The <code>invoke_for_each_value</code> function name itself, however, will be trimmed of its surrounding spaces.

{{vpad|1.5em}}

=== <code>magic_for_each_value</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>magic_for_each_value</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = [[#sequential|Sortable]] | data2 = Yes
| label3 = Often preceeded by | data3 = <code>[[#sequential|sequential]]</code>
| label4 = Relevant [[#setting|runtime variables]] | data4 = <code>h</code>, <code>i</code>, <code>f</code>, <code>n</code>
| header5 =  See also
| data6 = <code>[[#call_for_each_value|call_for_each_value]]</code>, <code>[[#invoke_for_each_value|invoke_for_each_value]]</code>, <code>[[#magic_for_each|magic_for_each]]</code>
}}

; Brief
: ''For each parameter passed to the caller template, call a magic word with at least one argument (i.e. the parameter's value)''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|magic_for_each_value|parser function|[append 1]|[append 2]|[...]|[append n]|[named param 1=value 1]|[...]|[named param n=value n]|[...]}}</syntaxhighlight>

Exactly like <code>[[#call_for_each_value|call_for_each_value]]</code>, but calls a [[:mw:Help:Magic words#Parser functions|parser function]] instead of a template.

For example, if a template had the following code,

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|setting|ih|&preloadparams%5b%5d{{=}}|magic_for_each_value|urlencode|QUERY}}</syntaxhighlight>

and were transcluded as <syntaxhighlight lang="wikitext" inline>{{example template|hello world|àèìòù|foo bar}}</syntaxhighlight>, the <code><nowiki>{{</nowiki>[[:mw:Help:Magic words#URL data|urlencode]]:...|QUERY<nowiki>}}</nowiki></code> parser function would be called for each incoming parameter as first argument and with <code>QUERY</code> as second argument, and finally the returned text would be prefixed with <code>&preloadparams%5b%5d=</code>. This would generate,

<pre>&preloadparams%5b%5d=hello+world&preloadparams%5b%5d=%C3%A0%C3%A8%C3%AC%C3%B2%C3%B9&preloadparams%5b%5d=foo+bar</pre>

which can be used to allow the creation of pages [[:mw:Manual:Creating pages with preloaded text#Using parameters|with preloaded text and parameters]].

{{vpad}}

{{A note}} All arguments passed to this function except the magic word are not trimmed of their leading and trailing spaces. The <code>magic_for_each_value</code> function name itself, however, will be trimmed of its surrounding spaces.

{{vpad|1.5em}}

=== <code>for_each</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Function <code>for_each</code>
| label1 = Num. of arguments | data1 = 1
| label2 = [[#sequential|Sortable]] | data2 = Yes
| label3 = Relevant [[#setting|runtime variables]] | data3 = <code>h</code>, <code>i</code>, <code>f</code>, <code>n</code>
| header4 =  See also
| data5 = <code>[[#list|list]]</code>, <code>[[#list_values|list_values]]</code>, {{mlx|for nowiki|}}, {{tl2|for nowiki}}
}}

; Brief
: ''For each parameter passed to the caller template, expand all occurrences of <code>$#</code> and <code>$@</code> within a given text as key and value respectively''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|for_each|wikitext}}</syntaxhighlight>

Example:

<syntaxhighlight lang="wikitext">{{#invoke:params|for_each|Arg name: $#, Arg value: $@}}</syntaxhighlight>

The text returned by this function is not expanded further (currently this module does not offer an <code>expand_for_each</code> function). If you need wikitext expansion, use <code>[[#concat_and_call|concat_and_call]]</code> to propagate the incoming parameters altogether to the {{tl|for nowiki}} template. Example:

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|concat_and_call|for nowiki|[separator]|<nowiki>{{{i}}} is {{urlencode:{{{1}}}|QUERY}}</nowiki>}}</syntaxhighlight>

{{vpad}}

{{A note}} The argument passed to this function is not trimmed of its leading and trailing spaces. The <code>for_each</code> function name itself, however, will be trimmed of its surrounding spaces.

{{vpad}}

== Modifiers (piping functions) ==
The following are ''modifiers'', i.e. functions that expect to be piped instead of returning to the caller. Each of them can be followed by either another modifier or a non-piping function.

{{vpad}}

=== <code>sequential</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>sequential</code>
| label1 = Num. of arguments | data1 = 0
| label2 = Repeatable | data2 = No
| label3 = Conflicts with | data3 = <code>[[#non-sequential|non-sequential]]</code>, <code>[[#all_sorted|all_sorted]]</code>
| header4 =  See also
| data5 = <code>[[#non-sequential|non-sequential]]</code>, <code>[[#all_sorted|all_sorted]]</code>, <code>[[#squeezing|squeezing]]</code>
}}

; Brief
: ''Reduce the parameter list to the subgroup of consecutive parameters that follow {{tjp|1:}}''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|sequential|pipe function name}}</syntaxhighlight>

Example:

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|count}}</syntaxhighlight>

This modifier does not take arguments besides the name of the function that will follow.

Using <code>sequential</code> together with <code>[[#non-sequential|non-sequential]]</code> will generate an error.

{{vpad}}

{{A note}} Like <code>[[#non-sequential|non-sequential]]</code>, the <code>sequential</code> modifier permanently marks a query. For instance, writing <syntaxhighlight lang="wikitext" inline>{{#invoke:params|sequential|with_name_not_matching|1|...}}</syntaxhighlight> will first mark the query as “sequential”, then will discard the first element from the sequence (leaving all the others intact). And so, no matter how many other parameters will be present, nothing will be shown.

{{vpad|1.5em}}

=== <code>non-sequential</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>non-sequential</code>
| label1 = Num. of arguments | data1 = 0
| label2 = Repeatable | data2 = No
| label3 = Conflicts with | data3 = <code>[[#sequential|sequential]]</code>
| header4 =  See also
| data5 = <code>[[#sequential|sequential]]</code>, <code>[[#all_sorted|all_sorted]]</code>
}}

; Brief
: ''Reduce the parameter list by discarding the subgroup of consecutive parameters that follow {{tjp|1:}}''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|non-sequential|pipe function name}}</syntaxhighlight>

Example:

<syntaxhighlight lang="wikitext">{{#invoke:params|non-sequential|setting|ih/p|{{!}}|{{=}}|list}}</syntaxhighlight>

This modifier does not take arguments besides the name of the function that will follow.

Using <code>non-sequential</code> together with <code>[[#sequential|sequential]]</code> will generate an error.

{{vpad}}

{{A note}} Like <code>[[#sequential|sequential]]</code>, the <code>non-sequential</code> modifier permanently marks a query, and no matter what transformations will follow (see <code>[[#squeezing|squeezing]]</code>) the parameters' “sequence” will not be shown.

{{vpad|1.5em}}

=== <code>all_sorted</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>all_sorted</code>
| label1 = Num. of arguments | data1 = 0
| label2 = Repeatable | data2 = No
| label3 = Conflicts with | data3 = <code>[[#sequential|sequential]]</code>
| label4 = Has no effects on | data4 = <code>[[#count|count]]</code>, <code>[[#value_of|value_of]]</code>, <code>[[#concat_and_call|concat_and_call]]</code>, <code>[[#concat_and_invoke|concat_and_invoke]]</code>
| header5 =  See also
| data6 = <code>[[#sequential|sequential]]</code>
}}

; Brief
: ''When the time will come, all parameters will be dispatched sorted: first the numerical ones, then the rest in alphabetical order''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|all_sorted|pipe function name}}</syntaxhighlight>

Example:

<syntaxhighlight lang="wikitext">{{#invoke:params|all_sorted|setting|ih/p|{{!}}|{{=}}|list}}</syntaxhighlight>

This modifier does not take arguments besides the name of the function that will follow.

Normally only sequential parameters are dispatched sorted, whereas non-sequential ones are dispatched randomly. The <code>all_sorted</code> modifier ensures that nothing is left out of (alphabetical) order. Attention must be paid to the fact that parameters whose name is a negative number will appear first. To avoid this the <code>[[#squeezing|squeezing]]</code> modifier can be used.<ref>To be precise, the order will not be strictly alphabetical, because this would imply that a template called with the following parameters <syntaxhighlight lang="wikitext" inline>{{foobar|-4=you|9=wanna|.=me?|11=marry|-8=do}}</syntaxhighlight> would see them reordered as follows: <syntaxhighlight lang="wikitext" inline>{{foobar|-8=do|-4=you|.=me?|9=wanna|11=marry}}</syntaxhighlight> (with the dot in the middle between negative and positive numbers). To avoid this, '''numbers are always displayd first''' (i.e. <syntaxhighlight lang="wikitext" inline>{{foobar|-8=do|-4=you|9=wanna|11=marry|.=me?}}</syntaxhighlight>).</ref>

The <code>all_sorted</code> modifier only affects the way parameters are shown, but has no effects on functions that do not iterate or cannot impose an order, such as:

* <code>[[#count|count]]</code>
* <code>[[#value_of|value_of]]</code>
* <code>[[#concat_and_call|concat_and_call]]</code>
* <code>[[#concat_and_invoke|concat_and_invoke]]</code>

{{vpad}}

{{A note}} The <code>all_sorted</code> modifier cannot be used with functions that propagate several parameters together in a single call, like <code>[[#concat_and_call|concat_and_call]]</code> and <code>[[#concat_and_invoke|concat_and_invoke]]</code>, because during a call the order of arguments is always lost. For the same reason, it is not possible to guess the order of named parameters a template was invoked with.

{{vpad|1.5em}}

=== <code>setting</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>setting</code>
| label1 = Num. of arguments | data1 = 2–6 (variable)
| label2 = Repeatable | data2 = Yes
| header3 =  Memory slots
| data4 = {{aligned table|fullwidth=y
  | col1header=y | col1style=display:block;
  | <code>i</code>| Iteration delimiter
  | <code>p</code>| Key-value delimiter
  | <code>h</code>| Header text
  | <code>f</code>| Footer text
  | <code>n</code>| Fallback text
 }}
}}

; Brief
: ''Define glue strings''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|directives|...|pipe function name}}</syntaxhighlight>

This modifier allows to set some internal variables that will be used by other functions. It takes a variable number of arguments, relying on the first argument to understand how many other arguments to read. A few examples will introduce it better than words:

* <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|i|{{!}}|list_values}}</syntaxhighlight>
*: ↳ Set the value of ''iteration delimiter'' to <code>|</code>, then list all values
* <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|ih|{{!}}|list_values}}</syntaxhighlight>
*: ↳ Set the value of both ''header text'' and ''iteration delimiter'' to <code>|</code>, then list all values
* <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|ih/p|{{!}}|{{=}}|list}}</syntaxhighlight>
*: ↳ Set the value of both ''header text'' and ''iteration delimiter'' to <code>|</code>, set ''key-value pair delimiter'' to <code>=</code>, then list all parameters
* <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|ih/p/n|{{!}}|{{=}}|No parameters were passed|list}}</syntaxhighlight>
*: ↳ Set the value of both ''header text'' and ''iteration delimiter'' to <code>|</code>, set ''key-value pair delimiter'' to <code>=</code>, set ''fallback text'' to <code>No parameters were passed</code>, then list all parameters

The first argument is a slash-separated list of lists of slots to assign; one slot is referred by exactly one character and each list of slots maps exactly one argument. A slot indicates which internal variable to set. If more than one slot is aggregated within the same slash-separated list the same text will be assigned to more than one variable.

The slots available are the following:

{| class="wikitable" style="margin-left: auto; margin-right: auto;"
|-
! Slots
! Variable
! Description
|-
| <code>i</code>
| ''Iteration delimiter''
| The string of text that will be placed between each iteration; it is never inserted unless there are two or more parameters to show.
|-
| <code>p</code>
| ''Key-value pair delimiter''
| The string of text that will be placed between each parameter name and its value; it is never inserted by functions that only iterate between values, or by functions that pass the key-value pairs to external calls.
|-
| <code>h</code>
| ''Header text''
| The string of text that will be placed before the iteration begins; it is inserted printed if there are no parameters to show.
|-
| <code>f</code>
| ''Footer text''
| The string of text that will be placed after the iteration is over; it is never inserted if there are no parameters to show.
|-
| <code>n</code>
| ''Fallback text''
| The string of text that will be placed if there are no parameters to show.
|}

In theory, instead of assigning different slots at once (i.e. <syntaxhighlight lang="wikitext" inline>{{...|setting|ih/p|{{!}}|{{=}}|...}}</syntaxhighlight>), it is possible to write separate invocations of <code>setting</code> for each variable, as in <syntaxhighlight lang="wikitext" inline>{{...|setting|ih|{{!}}|setting|p|{{=}}...}}</syntaxhighlight>. This method will be slightly less efficient.

{{vpad|1.5em}}

=== <code>squeezing</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>squeezing</code>
| label1 = Num. of arguments | data1 = 0
| label2 = Repeatable | data2 = Yes
| header3 =  See also
| data4 = <code>[[#sequential|sequential]]</code>
}}

; Brief
: ''Rearrange all parameters that have numerical names to form a compact sequence starting from 1, keeping the same order''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|squeezing|pipe function name}}</syntaxhighlight>

Example:

<syntaxhighlight lang="wikitext">{{#invoke:params|squeezing|sequential|setting|i/p|<br />|: |list}}</syntaxhighlight>

This modifier does not take arguments besides the name of the function that will follow.

The following three concatenations will lead to the same result of discarding all parameters with numerical names:

# <syntaxhighlight lang="wikitext" inline>{{...|non-sequential|squeezing|...}}</syntaxhighlight>
# <syntaxhighlight lang="wikitext" inline>{{...|squeezing|non-sequential|...}}</syntaxhighlight>
# <syntaxhighlight lang="wikitext" inline>{{...|with_name_not_matching|^%-?%d+$|...}}</syntaxhighlight>

{{vpad|1.5em}}

=== <code>cutting</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>cutting</code>
| label1 = Num. of arguments | data1 = 2
| label2 = Repeatable | data2 = Yes
| header3 =  See also
| data4 = <code>[[#sequential|sequential]]</code>, <code>[[#squeezing|squeezing]]</code>
}}

; Brief
: ''Remove zero or more parameters from the beginning and the end of the parameter list''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|cutting|left trim|right trim|pipe function name}}</syntaxhighlight>

The first argument indicates how many sequential parameters must be removed from the beginning of the parameter list, the second argument indicates how many sequential parameters must be removed from the end of the parameter list. If any of the two arguments is a negative number its absolute value indicates what must be left ''on the other side'' – i.e. <syntaxhighlight lang="wikitext" inline>{{#invoke:params|cutting|-3|0|list}}</syntaxhighlight> indicates that the last three arguments must not be discarded.

Example:

<syntaxhighlight lang="wikitext">{{#invoke:params|cutting|0|2|sequential|call_for_each_value|example template}}</syntaxhighlight>

If the absolute value of the sum of the two arguments (left and right cut) is greater than the number of sequential parameters available, the behavior will be the same as if the sum had been equal to the number of sequential parameters available, both when this is a positive value and when it is a negative value (with opposite results). After the desired sequential parameters have been discarded all numerical parameters will be shifted accordingly.

In some cases it might be necessary to concatenate more than one invocation of the <code>cutting</code> function. For instance, notice the <code><nowiki>|cutting|1|0|cutting|-1|0</nowiki></code> code in the following imaginary <code><nowiki>{{Foobar see also}}</nowiki></code> template in order to properly show the “and” conjunction and possibly an [[Serial comma|Oxford comma]] when more than two page names are provided:

<syntaxhighlight lang="wikitext">{{Hatnote|{{{altphrase|Foobar see also}}}: {{#if:{{{1|}}}
		|[[{{trim|{{{1|}}}}}]]{{#invoke:params|sequential|squeezing|cutting|1|1|setting|ih|, |trimming_values|for_each|[[$@]]}}{{#invoke:params|sequential|squeezing|cutting|1|0|cutting|-1|0|setting|h|{{#if:{{{3|}}}|,}} and |trimming_values|for_each|[[$@]]}}
		|{{Error|{{tl|Foobar see also}} requires at least one page name}}
	}}
}}</syntaxhighlight>

{{A note|Suggestion:}} Although <syntaxhighlight lang="wikitext" inline>{{#invoke:params|cutting|-1|1|...}}</syntaxhighlight> de facto gets rid of all sequential parameters, it is clearer and more idiomatic to write <syntaxhighlight lang="wikitext" inline>{{#invoke:params|non-sequential|...}}</syntaxhighlight> to obtain the same effect. Writing <syntaxhighlight lang="wikitext" inline>{{#invoke:params|sequential|cutting|-1|1|...}}</syntaxhighlight> will leave zero arguments to show.

{{vpad|1.5em}}

=== <code>with_name_matching</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>with_name_matching</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = Repeatable | data2 = Yes
| header3 =  See also
| data4 = <code>[[#with_name_not_matching|with_name_not_matching]]</code>, <code>[[#with_value_matching|with_value_matching]]</code>, <code>[[#with_value_not_matching|with_value_not_matching]]</code>
}}

; Brief
: ''Discard all parameters whose name ''does not match '''all''''' the given patterns''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|with_name_matching|pattern 1|[plain flag 1]|[or]|[pattern 2]|[plain flag 2]|[or]|[...]|[pattern N]|[plain flag N]|pipe function name}}</syntaxhighlight>

Internally this modifier uses Lua's <code>[[:mw:Extension:Scribunto/Lua reference manual#string.find|string.find()]]</code> function to find whether parameter names match against given patterns; therefore, unless a target string is set to <code>plain</code>, please use the same syntax of [[:mw:Extension:Scribunto/Lua reference manual#Patterns|Lua patterns]]. The plain flag can be either <code>plain</code> or omitted. When omitted it is assumed that the target string is a Lua pattern.

To express a [[Disjunction (logical connective)|logical OR]] the <code>or</code> keyword is available. To express a [[Logical conjunction|logical AND]] instead, concatenate more invocations of <code>with_name_matching</code>.

{{vpad}}

For the sake of argument we will imagine that we are invoking <code>with_name_matching</code> from within the {{tl|Infobox artery}} template, and this is being called with the following parameters:

{{tj|Infobox artery
	| Name: Pulmonary artery
	| Latin: truncus pulmonalis, arteria pulmonalis
	| Image: <nowiki>{{Heart diagram 250px}}</nowiki>
	| Caption: Anterior (frontal) view of the opened heart. (Pulmonary artery upper right.)
	| Image2: Alveoli diagram.png
	| Caption2: Diagram of the alveoli with both cross-section and external view.
	| BranchFrom: <nowiki>[[right ventricle]]</nowiki>
	| BranchTo: 
	| Vein: <nowiki>[[pulmonary vein]]</nowiki>
	| Precursor: truncus arteriosus
	| Supplies: 
}}

{{vpad}}

Test cases:

* List only the parameters whose names match against the <code>^Image</code> pattern:
*: ↳ <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_matching|^Image|list}}</syntaxhighlight>
*:: ↳ {{highlight round|bc=#ff9|<nowiki>|Image={{Heart diagram 250px}}|Image2=Alveoli diagram.png</nowiki>}}
* List the parameters whose names match against both patterns <code>^Image</code> '''and''' <code>%d+$</code>:
*: ↳ <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_matching|^Image|with_name_matching|%d+$|list}}</syntaxhighlight>
*:: ↳ {{highlight round|bc=#ff9|<nowiki>|Image2=Alveoli diagram.png</nowiki>}}
* List the parameters whose names match against either the <code>^Name</code> '''or''' the <code>^Latin$</code> pattern:
*: ↳ <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_matching|^Name$|or|^Latin$|list}}</syntaxhighlight>
*:: ↳ {{highlight round|bc=#ff9|<nowiki>|Latin=truncus pulmonalis, arteria pulmonalis|Name=Pulmonary artery</nowiki>}}
* List the parameters whose names match against either the <code>ma</code> plain string '''or''' the <code>me$</code> pattern:
*: ↳ <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_matching|ma|plain|or|me$|list}}</syntaxhighlight>
*:: ↳ {{highlight round|bc=#ff9|<nowiki>|Image={{Heart diagram 250px}}|Name=Pulmonary artery|Image2=Alveoli diagram.png</nowiki>}}

{{vpad}}

{{A note}} The pattern arguments passed to this function are not trimmed of their leading and trailing spaces. The <code>or</code> and <code>plain</code> keywords, and the <code>with_name_matching</code> function name itself, however, will be trimmed of their surrounding spaces.

{{vpad|1.5em}}

=== <code>with_name_not_matching</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>with_name_not_matching</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = Repeatable | data2 = Yes
| header3 =  See also
| data4 = <code>[[#with_name_matching|with_name_matching]]</code>, <code>[[#with_value_matching|with_value_matching]]</code>, <code>[[#with_value_not_matching|with_value_not_matching]]</code>
}}

; Brief
: ''Discard all parameters whose name ''matches '''all''''' the given patterns''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|with_name_not_matching|pattern 1|[plain flag 1]|[and]|[pattern 2]|[plain flag 2]|[and]|[...]|[pattern N]|[plain flag N]|pipe function name}}</syntaxhighlight>

Internally this modifier uses Lua's <code>[[:mw:Extension:Scribunto/Lua reference manual#string.find|string.find()]]</code> function to find whether parameter names match against given patterns; therefore, unless a target string is set to <code>plain</code>, please use the same syntax of [[:mw:Extension:Scribunto/Lua reference manual#Patterns|Lua patterns]]. The plain flag can be either <code>plain</code> or omitted. When omitted it is assumed that the target string is a Lua pattern.

To express a [[Disjunction (logical connective)|logical OR]] the <code>or</code> keyword is available. To express a [[Logical conjunction|logical AND]] instead, concatenate more invocations of <code>with_name_not_matching</code>.

{{vpad}}

For the sake of argument we will imagine that we are invoking <code>with_name_not_matching</code> from within the {{tl|Infobox artery}} template, and this is being transcluded using the same parameters that we had imagined in the previous example at <code>[[#with_name_matching|with_name_matching]]</code>:

* List only the parameters whose names do not match against the <code>a</code> pattern:
*: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_not_matching|a|list}}</syntaxhighlight>
*:: ↳ {{highlight round|bc=#ff9|<nowiki>|Precursor=truncus arteriosus|Supplies=|Vein=pulmonary vein</nowiki>}}
* List the parameters whose names do not match against the <code>a</code> plain string '''and''' do not match against the <code>l</code> plain string either:
*: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_not_matching|a|plain|with_name_not_matching|l|plain|list}}</syntaxhighlight>
*:: ↳ {{highlight round|bc=#ff9|<nowiki>|Precursor=truncus arteriosus|Vein=pulmonary vein</nowiki>}}
* List the parameters whose names do not match against either the <code>a</code> plain string '''or''' the <code>n</code> plain string:
*: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_not_matching|a|plain|or|n|plain|list}}</syntaxhighlight>
*:: ↳ {{highlight round|bc=#ff9|<nowiki>|Precursor=truncus arteriosus|Supplies=|Image={{Heart diagram 250px}}|Name=Pulmonary artery|Image2=Alveoli diagram.png|Vein=pulmonary vein</nowiki>}}

{{vpad}}

It is possible to use this function to check for unknown parameters:

<syntaxhighlight lang="wikitext">{{#ifexpr:{{#invoke:params|with_name_not_matching|^hello$|with_name_not_matching|^wind$|count}} > 0
	|{{#invoke:Error|error|Error: The only parameters accepted are {{para|hello}} and {{para|wind}}.}}
	|Everything is good: do something
}}</syntaxhighlight>

For simple cases like this, however, specialized modules are available; you might want to have a look at:

* {{ml|Check for unknown parameters|check}}
* {{ml|Check for deprecated parameters|check}}
* {{ml|Check for clobbered parameters|check}}
* {{ml|Parameter validation|validateparams}}
* {{ml|TemplatePar|valid}}

{{vpad}}

{{A note}} The pattern arguments passed to this function are not trimmed of their leading and trailing spaces. The <code>or</code> and <code>plain</code> keywords, and the <code>with_name_not_matching</code> function name itself, however, will be trimmed of their surrounding spaces.

{{vpad|1.5em}}

=== <code>with_value_matching</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>with_value_matching</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = Repeatable | data2 = Yes
| header3 =  See also
| data4 = <code>[[#with_name_matching|with_name_matching]]</code>, <code>[[#with_name_not_matching|with_name_not_matching]]</code>, <code>[[#with_value_not_matching|with_value_not_matching]]</code>
}}

; Brief
: ''Discard all parameters whose value ''does not match '''all''''' the given patterns''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|with_value_matching|pattern 1|[plain flag 1]|[or]|[pattern 2]|[plain flag 2]|[or]|[...]|[pattern N]|[plain flag N]|pipe function name}}</syntaxhighlight>

Exactly like <code>[[#with_name_matching|with_name_matching]]</code>, but applied to parameter values instead of names.

Internally this modifier uses Lua's <code>[[:mw:Extension:Scribunto/Lua reference manual#string.find|string.find()]]</code> function to find whether parameter names match against given patterns; therefore, unless a target string is set to <code>plain</code>, please use the same syntax of [[:mw:Extension:Scribunto/Lua reference manual#Patterns|Lua patterns]]. The plain flag can be either <code>plain</code> or omitted. When omitted it is assumed that the target string is a Lua pattern.

Example:

<syntaxhighlight lang="wikitext">{{#invoke:params|with_value_matching|banana|count}}</syntaxhighlight>

{{vpad}}

{{A note}} The pattern arguments passed to this function are not trimmed of their leading and trailing spaces. The <code>or</code> and <code>plain</code> keywords, and the <code>with_value_matching</code> function name itself, however, will be trimmed of their surrounding spaces.

{{vpad|1.5em}}

=== <code>with_value_not_matching</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>with_value_not_matching</code>
| label1 = Num. of arguments | data1 = ''Ad libitum''
| label2 = Repeatable | data2 = Yes
| header3 =  See also
| data4 = <code>[[#with_name_matching|with_name_matching]]</code>, <code>[[#with_name_not_matching|with_name_not_matching]]</code>, <code>[[#with_value_matching|with_value_matching]]</code>
}}

; Brief
: ''Discard all parameters whose value ''matches '''all''''' the given patterns''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|with_value_not_matching|pattern 1|[plain flag 1]|[and]|[pattern 2]|[plain flag 2]|[and]|[...]|[pattern N]|[plain flag N]|pipe function name}}</syntaxhighlight>

Exactly like <code>[[#with_name_not_matching|with_name_not_matching]]</code>, but applied to parameter values instead of names.

Internally this modifier uses Lua's <code>[[:mw:Extension:Scribunto/Lua reference manual#string.find|string.find()]]</code> function to find whether parameter names match against given patterns; therefore, unless a target string is set to <code>plain</code>, please use the same syntax of [[:mw:Extension:Scribunto/Lua reference manual#Patterns|Lua patterns]]. The plain flag can be either <code>plain</code> or omitted. When omitted it is assumed that the target string is a Lua pattern.

For instance, before calling <code>[[#list|list]]</code>, the following code will get rid of all blank parameters (i.e. parameters whose values contain only zero or more spaces):

<syntaxhighlight lang="wikitext">{{#invoke:params|with_value_not_matching|^%s*$|setting|hi/p|{{!}}|{{=}}|list}}</syntaxhighlight>

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{{A note}} The pattern arguments passed to this function are not trimmed of their leading and trailing spaces. The <code>or</code> and <code>plain</code> keywords, and the <code>with_value_not_matching</code> function name itself, however, will be trimmed of their surrounding spaces.

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=== <code>trimming_values</code> ===
{{Infobox|headerstyle=background:lavender
| titlestyle = font-weight:normal; font-size:100%;
| title = Modifier <code>trimming_values</code>
| label1 = Num. of arguments | data1 = 0
| label2 = Repeatable | data2 = No
}}

; Brief
: ''Remove leading and trailing spaces from values''
; Syntax
: <syntaxhighlight lang="wikitext" inline>{{#invoke:params|trimming_values|pipe function name}}</syntaxhighlight>

This modifier does not take arguments besides the name of the function that will follow.

Most modifiers are order-dependent, therefore placing <code>trimming_values</code> in different positions can generate different results. For instance, imagining our <code><nowiki>{{Example template}}</nowiki></code> being called with the following spaced arguments: <syntaxhighlight lang="wikitext" inline>{{Example template| wanna | be | my | friend | ? }}</syntaxhighlight>, if <code><nowiki>{{Example template}}</nowiki></code> contained the following code,

<syntaxhighlight lang="wikitext">{{#invoke:params|with_value_matching|%s+$|trimming_values|setting|i/p|{{!}}|{{=}}|list}}</syntaxhighlight>

the following text would be printed: <code>1=wanna|2=be|3=my|4=friend|5=?</code>. But if instead it contained the following code,

<syntaxhighlight lang="wikitext">{{#invoke:params|trimming_values|with_value_matching|%s+$|setting|i/p|{{!}}|{{=}}|list}}</syntaxhighlight>

no arguments would be shown.

Order affects also performance, and how many values will be trimmed of their leading and trailing spaces will depend on where <code>trimming_values</code> is placed. For instance, if a template were invoked with 50 parameters and its code contained <syntaxhighlight lang="wikitext" inline>{{#invoke:params|trimming_values|cutting|-1|0|list}}</syntaxhighlight>, first all its values would be trimmed of leading and trailing blank spaces and then its first 49 parameters would be discarded. On the other hand, writing <syntaxhighlight lang="wikitext" inline>{{#invoke:params|cutting|-1|0|trimming_values|list}}</syntaxhighlight> would first discard 49 parameters and then trim the only value left, resulting in a more efficient code. As a general rule, placing <code>trimming_values</code> as the last modifier is always the best choice.

Placing <code>trimming_values</code> together with <code>non-sequential</code> will result in an empty call with no effects, because non-sequential parameters are stripped of their leading and trailing spaces by default.

Using <code>trimming_values</code> makes this module behave like many Wikipedia modules behave. For example, if we wanted to emulate {{ml|Separated entries|main}}, writing

<syntaxhighlight lang="wikitext">{{#invoke:params|sequential|squeezing|trimming_values|setting|i|XXXX|list_values}}</syntaxhighlight>

will be equivalent to writing,

<syntaxhighlight lang="wikitext">{{#invoke:separated entries|main|separator=XXXX}}</syntaxhighlight>

whereas writing

<syntaxhighlight lang="wikitext">{{trim|{{{1|}}}}}{{#invoke:params|sequential|squeezing|cutting|1|1|trimming_values|setting|ih|XXXX|list_values}}{{#invoke:params|sequential|squeezing|cutting|1|0|cutting|-1|0|trimming_values|setting|h|YYYY|value_of|1}}</syntaxhighlight>

will be equivalent to writing

<syntaxhighlight lang="wikitext">{{#invoke:separated entries|main|separator=XXXX|conjunction=YYYY}}</syntaxhighlight>

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== Notes ==
<references />

== See also ==
* {{ml|TemplatePar}}
* {{ml|ParameterCount}}
* {{ml|Separated entries|main}}
* {{ml|Enumerate|main}}
* {{ml|Check for unknown parameters|check}}
* {{ml|Check for deprecated parameters|check}}
* {{ml|Check for clobbered parameters|check}}
* {{ml|Parameter validation}}
* {{ml|Expand wikitext|main}}
* {{ml|For loop|main}} and {{tl|For loop}}
* {{ml|For nowiki|main}} and {{tl|For nowiki}}
* [[Project:TemplateData]]

<includeonly>{{Sandbox other||
<!-- Categories below this line; interwikis at Wikidata -->
[[Category:Unknown parameters]]
[[Category:Wikipedia metatemplates]]
[[Category:Wikipedia utility modules]]
}}</includeonly>