Module:Params/doc

The {{#invoke:params}} 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 templates, 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. Under ./testcases you can find helper templates that can be specifically used for testing the module's capabilities in flexible ways (see in particular the {{./testcases/tmulti}} template).

 Note: In case your template uses this module, please add {{lua|Module:Params}} to its 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 templates' incoming parameters. As this makes it necessary to keep the argument slots clean from interference, instead of named arguments in order to specify options this module uses piping functions (i.e. functions that expect to be piped instead of returning to the caller), or modifiers. This creates a syntax similar to the following example:

{{#invoke:params|[modifier]|[...]|[modifier]|[...]|function|[...]}}

For instance, as the name suggests, the list 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 setting modifier, we are able to declare a key-value delimiter (p) and an iteration delimiter (i). And so, if we imagined a template named {{Example template}} containing the following wikitext,

{{#invoke:params|setting|i/p|<br />|: |list}}

and such template were called with the following arguments,

{{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
Beast of Bodmin: A large feline inhabiting Bodmin Moor
Morgawr: A sea serpent

We can also do more sophisticated things; for instance, by exploiting the possibility to set a header (h) and a footer (f), we can transform the previous code into a generator of definition lists,

{{#invoke:params|setting|h/p/i/f|<dl><dt>|</dt><dd>|</dd><dt>|</dd></dl>|list}}

thus yielding:

Beast of Bodmin

A large feline inhabiting Bodmin Moor

Morgawr

A sea serpent

Owlman

A giant owl-like creature

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

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

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:

{{#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}}

The two modifiers sequential and non-sequential 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 |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.

self

Function self

Num. of arguments	0
Not affected by	Any modifier
See also
{{FULLPAGENAME}}

Brief

Returns the name of the template that is calling this module

Syntax

{{#invoke:params|self}}

This argumentless function guarantees that the name of the template invoking this module is shown, regardless if this is transcluded or not.

As a possible example, if a Wikipedia page named Page X contained only a transclusion of a template named {{Foo bar}}, and the latter contained the following wikitext,

{{#invoke:params|self}}

{{FULLPAGENAME}}

if we visited Template:Foo bar we would see,

Template:Foo bar

Template:Foo bar

whereas if we visited Page X we would see:

Template:Foo bar

Page X

Therefore by writing

{{#ifeq:{{#invoke:params|self}}|{{FULLPAGENAME}}
	|Page is not being transcluded
	|Page is being transcluded
}}

it is possible to understand whether a page is being transcluded or not.

If Page X transcluded {{Foo bar 2}} and the latter were a redirect to {{Foo bar}}, we would still see

Template:Foo bar

Page X

A typical use case of this function is that of providing stable links for editing transcluded templates. E.g.:

{{edit|{{#invoke:params|self}}|edit this template}}

Another possible use case is that of transcluding a subtemplate. E.g.:

{{{{#invoke:params|self}}/my subtemplate|foo|bar}}

count

Function count

Num. of arguments	0
Often preceeded by	sequential
Not affected by	all_sorted, mapping…_by_calling, mapping…by_invoking, …blindly_by_calling, …lindly_by_invoking
See also
{{#invoke:ParameterCount}}

Brief

Count the number of parameters wherewith a template was called

Syntax

{{#invoke:params|count}}

This function does not take arguments.

The number that this function yields depends on the modifiers that precede it. For instance, in a template that is called with both named and unnamed arguments,

{{#invoke:params|count}}

and

{{#invoke:params|sequential|count}}

will return different results.

concat_and_call

Function concat_and_call

Num. of arguments	Ad libitum
Not affected by	all_sorted
See also
concat_and_invoke, concat_and_magic

Brief

Prepend numerical arguments to the current parameters or impose non-numerical arguments, then propagate everything to a custom template

Syntax

{{#invoke:params|concat_and_call|template name|[prepend 1]|[prepend 2]|[...]|[prepend n]|[named item 1=value 1]|[...]|[named item n=value n]|[...]}}

For example, if our {{Example template}} had the following code,

{{#invoke:params|concat_and_call|foo bar|elbow|earth|room|7=classy|hello=not today}}

and were called with,

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

the following call to the {{Foo bar}} template would be performed:

{{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.

 Note: All arguments passed to this function except the template name are not trimmed of their leading and trailing spaces. The concat_and_call function name itself, however, will be trimmed of its surrounding spaces.

concat_and_invoke

Function concat_and_invoke

Num. of arguments	Ad libitum
Not affected by	all_sorted
See also
concat_and_call, concat_and_magic

Brief

Prepend numerical arguments to the current parameters, or impose non-numerical arguments; then propagate everything to a custom module

Syntax

{{#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]|[...]}}

Exactly like concat_and_call, but invokes a module instead of calling a template.

 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 concat_and_invoke function name itself, however, will be trimmed of its surrounding spaces.

concat_and_magic

Function concat_and_magic

Num. of arguments	Ad libitum
Not affected by	all_sorted
See also
concat_and_call, concat_and_invoke

Brief

Prepend numerical arguments to the current parameters, or impose non-numerical arguments; then propagate everything to a custom parser function

Syntax

{{#invoke:params|concat_and_magic|parser function|[prepend 1]|[prepend 2]|[...]|[prepend n]|[named item 1=value 1]|[...]|[named item n=value n]|[...]}}

Exactly like concat_and_call, but calls a parser function instead of a template.

 Note: All arguments passed to this function except the magic word are not trimmed of their leading and trailing spaces. The concat_and_magic function name itself, however, will be trimmed of its surrounding spaces.

value_of

Function value_of

Num. of arguments	1
Relevant runtime variables	h, f, n
Not affected by	all_sorted
See also
list_values

Brief

Get the value of a single parameter

Syntax

{{#invoke:params|value_of|parameter name}}

Without modifiers this function is similar to writing {{{parameter name|}}}. With modifiers, however, it allows to reach parameters that would be unreachable without knowing their number in advance. For instance, writing

{{#invoke:params|cutting|-2|0|value_of|1}}

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 (h), a footer (f), and a fallback text (n) can be declared via the setting modifier – the strings assigned to the key-value pair delimiter (p), the iteration delimiter (i) and the last iteration delimiter (l) will be ignored.

list

Function list

Num. of arguments	Ad libitum
Sortable	Yes
Relevant runtime variables	h, p, i, l, f, n
See also
list_values

Brief

List the template parameters (both their names and their values)

Syntax

{{#invoke:params|list}}

This function does not take arguments.

If the setting 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 (h), a key-value pair delimiter (p), an iteration delimiter (i), a last iteration delimiter (l), a footer (f), and a fallback text (n) can be declared via setting.

For example, the following code

{{#invoke:params|setting|h/i/p/f/n|'''Parameters passed:''' |); | (|)|'''No parameters were passed'''|list}}

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)

list_values

Function list_values

Num. of arguments	Ad libitum
Sortable	Yes
Often preceeded by	sequential
Relevant runtime variables	h, i, l, f, n
See also
list, value_of, {{#invoke:separated entries}}

Brief

List the values of the incoming parameters

Syntax

{{#invoke:params|list_values}}

This function does not take arguments.

The sequential modifier often accompanies this function. If the setting 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 (h), an iteration delimiter (i), a last iteration delimiter (l), a footer (f), and a fallback text (n) can be declared via setting – the string assigned to the key-value pair delimiter (p) will be ignored.

For example, the following code

{{#invoke:params|setting|h/i/p/f/n|'''Parameters passed:''' |); | (|)|'''No parameters were passed'''|list_values}}

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.

call_for_each

Function call_for_each

Num. of arguments	Ad libitum
Sortable	Yes
Relevant runtime variables	h, i, l, f, n
See also
call_for_each_value, invoke_for_each, magic_for_each, {{#invoke:for loop}}, {{for loop}}

Brief

For each parameter passed to the caller template, call a custom template with at least two parameters (key and value)

Syntax

{{#invoke:params|call_for_each|template name|[append 1]|[append 2]|[...]|[append n]|[named param 1=value 1]|[...]|[named param n=value n]|[...] }}

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

Calling a template for each key-value pair with

{{#invoke:params|sequential|call_for_each|foobar}}

will be different from writing

{{#invoke:params|sequential|for_each|{{foobar|$#|$@}}}}

In the first example each key-value pair will be passed to the {{foobar}} template, while in the second example the $# and $@ tokens will be expanded after the {{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.

 Note: All arguments passed to this function except the template name are not trimmed of their leading and trailing spaces. The call_for_each function name itself, however, will be trimmed of its surrounding spaces.

invoke_for_each

Function invoke_for_each

Num. of arguments	Ad libitum
Sortable	Yes
Relevant runtime variables	h, i, l, f, n
See also
invoke_for_each_value, call_for_each, magic_for_each

Brief

For each parameter passed to the caller template, invoke a custom module function with at least two arguments (key and value)

Syntax

{{#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]|[...]}}

Exactly like call_for_each, but invokes a module instead of calling a template.

Invoking a module function for each key-value pair with

{{#invoke:params|sequential|invoke_for_each|foobar|main}}

will be different from writing

{{#invoke:params|sequential|for_each|{{#invoke:foobar|main|$#|$@}}}}

In the first example each key-value pair will be passed to the {{#invoke:foobar|main}} module function, while in the second example the $# and $@ 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.

 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 invoke_for_each function name itself, however, will be trimmed of its surrounding spaces.

magic_for_each

Function magic_for_each

Num. of arguments	Ad libitum
Sortable	Yes
Relevant runtime variables	h, i, l, f, n
See also
magic_for_each_value, call_for_each, invoke_for_each

Brief

For each parameter passed to the caller template, call a magic word with at least two arguments (key and value)

Syntax

{{#invoke:params|magic_for_each|parser function|[append 1]|[append 2]|[...]|[append n]|[named param 1=value 1]|[...]|[named param n=value n]|[...]}}

Exactly like call_for_each, but calls a parser function instead of a template.

 Note: All arguments passed to this function except the magic word are not trimmed of their leading and trailing spaces. The magic_for_each function name itself, however, will be trimmed of its surrounding spaces.

call_for_each_value

Function call_for_each_value

Num. of arguments	Ad libitum
Sortable	Yes
Often preceeded by	sequential
Relevant runtime variables	h, i, l, f, n
See also
call_for_each, invoke_for_each_value, magic_for_each_value, {{#invoke:for loop}}, {{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

{{#invoke:params|call_for_each_value|template name|[append 1]|[append 2]|[...]|[append n]|[named param 1=value 1]|[...]|[named param n=value n]|[...]}}

The sequential modifier often 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 (h), an iteration delimiter (i), a last iteration delimiter (l), a footer (f), and a fallback text (n) can be declared via the setting modifier – the string assigned to the key-value pair delimiter (p) will be ignored.

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

{{#invoke:params|sequential|setting|i|, |call_for_each_value|tl}}

This will be different from writing

{{#invoke:params|sequential|setting|i|, |for_each|{{tl|$@}}}}

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

 Note: All arguments passed to this function except the template name are not trimmed of their leading and trailing spaces. The call_for_each_value function name itself, however, will be trimmed of its surrounding spaces.

invoke_for_each_value

Function invoke_for_each_value

Num. of arguments	Ad libitum
Sortable	Yes
Often preceeded by	sequential
Relevant runtime variables	h, i, l, f, n
See also
call_for_each_value, invoke_for_each, magic_for_each_value

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

{{#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]|[...]}}

Exactly like call_for_each_value, but invokes a module instead of calling a template.

Invoking a module function for each value with

{{#invoke:params|sequential|invoke_for_each_value|foobar|main}}

will be different from writing

{{#invoke:params|sequential|for_each|{{#invoke:foobar|main|$@}}}}

In the first example each value will be passed to the {{#invoke:foobar|main}} module function, while in the second example the $@ 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.

 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 invoke_for_each_value function name itself, however, will be trimmed of its surrounding spaces.

magic_for_each_value

Function magic_for_each_value

Num. of arguments	Ad libitum
Sortable	Yes
Often preceeded by	sequential
Relevant runtime variables	h, i, l, f, n
See also
call_for_each_value, invoke_for_each_value, magic_for_each

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

{{#invoke:params|magic_for_each_value|parser function|[append 1]|[append 2]|[...]|[append n]|[named param 1=value 1]|[...]|[named param n=value n]|[...]}}

Exactly like call_for_each_value, but calls a parser function instead of a template.

For example, if a template had the following code,

{{#invoke:params|sequential|setting|ih|&preloadparams%5b%5d{{=}}|magic_for_each_value|urlencode|QUERY}}

and were transcluded as {{example template|hello world|àèìòù|foo bar}}, the {{urlencode:...|QUERY}} parser function would be called for each incoming parameter as first argument and with QUERY as second argument, and finally the returned text would be prefixed with &preloadparams%5b%5d=. This would generate,

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

which can be used to allow the creation of pages with preloaded text and parameters.

 Note: All arguments passed to this function except the magic word are not trimmed of their leading and trailing spaces. The magic_for_each_value function name itself, however, will be trimmed of its surrounding spaces.

for_each

Function for_each

Num. of arguments	1
Sortable	Yes
Relevant runtime variables	h, i, l, f, n
See also
list, list_values, {{#invoke:for nowiki}}, {{for nowiki}}

Brief

For each parameter passed to the caller template, expand all occurrences of $# and $@ within a given text as key and value respectively

Syntax

{{#invoke:params|for_each|wikitext}}

Example:

{{#invoke:params|for_each|Arg name: $#, Arg value: $@}}

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

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

 Note: The argument passed to this function is not trimmed of its leading and trailing spaces. The for_each function name itself, however, will be trimmed of its surrounding spaces.

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. The actions that modifiers do are done sequentially, in the same order chosen during the invocation of this module. Some modifiers, however, after signaling their presence to the modifiers that might follow, add their action to the queue of actions that will be done last (e.g. sequential, non-sequential, all_sorted).

sequential

Modifier sequential

Num. of arguments	0
Repeatable	No
Conflicts with	non-sequential, all_sorted
See also
non-sequential, all_sorted, squeezing

Brief

Reduce the parameter list to the subgroup of consecutive parameters that follow |1=

Syntax

{{#invoke:params|sequential|pipe function name}}

Example:

{{#invoke:params|sequential|count}}

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

Using sequential together with non-sequential will generate an error.

 Note: Like non-sequential, the sequential modifier permanently marks a query. For instance, writing {{#invoke:params|sequential|with_name_not_matching|1|...}} 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.

non-sequential

Modifier non-sequential

Num. of arguments	0
Repeatable	No
Conflicts with	sequential
See also
sequential, all_sorted

Brief

Reduce the parameter list by discarding the subgroup of consecutive parameters that follow |1=

Syntax

{{#invoke:params|non-sequential|pipe function name}}

Example:

{{#invoke:params|non-sequential|setting|ih/p|{{!}}|{{=}}|list}}

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

Using non-sequential together with sequential will generate an error.

 Note: Like sequential, the non-sequential modifier permanently marks a query, and no matter what transformations will follow (see squeezing) the parameters' “sequence” will not be shown.

all_sorted

Modifier all_sorted

Num. of arguments	0
Repeatable	No
Conflicts with	sequential
Has no effects on	count, value_of, concat_and_call, concat_and_invoke, concat_and_magic
See also
sequential

Brief

When the time will come, all parameters will be dispatched sorted: first the numerical ones, then the rest in alphabetical order

Syntax

{{#invoke:params|all_sorted|pipe function name}}

Example:

{{#invoke:params|all_sorted|setting|ih/p|{{!}}|{{=}}|list}}

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 all_sorted 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 squeezing modifier can be used.

The all_sorted 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:

• count
• value_of
• concat_and_call
• concat_and_invoke
• concat_and_magic

 Note: The all_sorted modifier cannot be used with functions that propagate several parameters together in a single call, like concat_and_call, concat_and_invoke, and concat_and_magic, 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.

setting

Modifier setting

Num. of arguments	2–7 (variable)
Repeatable	Yes
Memory slots
p Key-value delimiter i Iteration delimiter l Last iteration delimiter h Header text f Footer text n Fallback text

Brief

Define glue strings

Syntax

{{#invoke:params|setting|directives|...|pipe function name}}

This modifier allows to set some internal variables that will be used by 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:

• {{#invoke:params|setting|i|{{!}}|list_values}}

  ↳ Set the value of iteration delimiter to |, then list all values

• {{#invoke:params|setting|ih|{{!}}|list_values}}

  ↳ Set the value of both header text and iteration delimiter to |, then list all values

• {{#invoke:params|setting|ih/p|{{!}}|{{=}}|list}}

  ↳ Set the value of both header text and iteration delimiter to |, set key-value pair delimiter to =, then list all parameters

• {{#invoke:params|setting|ih/p/n|{{!}}|{{=}}|No parameters were passed|list}}

  ↳ Set the value of both header text and iteration delimiter to |, set key-value pair delimiter to =, set fallback text to No parameters were passed, 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:

Slots	Variable	Description
p	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.
i	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 when l is not given, or three or more parameters when l is given.
l	Last iteration delimiter	The string of text that will be placed between the second last and the last iteration; it is never inserted unless there are two or more parameters to show; if omitted defaults to i.
h	Header text	The string of text that will be placed before the iteration begins; it is never inserted if there are no parameters to show.
f	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.
n	Fallback text	The string of text that will be placed if there are no parameters to show.

All space characters in the directives arguments are discarded. Therefore writing {{#invoke:params|setting|ih/p|...}} is equivalent to writing

{{#invoke:params|setting| i
	h	/ p |...}}

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

Sometimes it might be necessary to make the values assigned depend on conditional expressions. For instance, the following imaginary {{Foobar see also}} template uses the #ifexpr parser function to properly show the “and” conjunction and possibly an Oxford comma when more than two page names are provided:

{{Hatnote|{{{altphrase|Foobar see also}}}: {{#if:{{{1|}}}
	|{{#invoke:params|sequential|squeezing|setting|i/l|, |{{#ifexpr:{{#invoke:params|sequential|squeezing|count}} > 2|,}} and |trimming_values|for_each|[[$@]]}}
	|{{Error|{{tl|Foobar see also}} requires at least one page name}}
}}}}

You can find this example at {{./examples/Oxford comma}}. E.g., {{module:params/doc/examples/Oxford comma|Latin|English|German|Italian}} will generate

 Note: The setting modifier will be trimmed of its surrounding spaces. The directives argument will be stripped of all space characters, including internal spaces. All the other arguments passed to this modifier will be parsed verbatim (i.e. leading and trailing spaces will not be removed).

squeezing

Modifier squeezing

Num. of arguments	0
Repeatable	Yes
See also
sequential

Brief

Rearrange all parameters that have numerical names to form a compact sequence starting from 1, keeping the same order

Syntax

{{#invoke:params|squeezing|pipe function name}}

Example:

{{#invoke:params|squeezing|sequential|setting|i/p|<br />|: |list}}

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:

1. {{...|non-sequential|squeezing|...}}
2. {{...|squeezing|non-sequential|...}}
3. {{...|with_name_not_matching|^%-?%d+$|...}}

cutting

Modifier cutting

Num. of arguments	2
Repeatable	Yes
See also
sequential, squeezing

Brief

Remove zero or more parameters from the beginning and the end of the parameter list

Syntax

{{#invoke:params|cutting|left trim|right trim|pipe function name}}

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 contains a negative number its absolute value indicates what must be left on the other side – i.e. {{#invoke:params|cutting|-3|0|list}} indicates that the last three arguments must not be discarded.

Example:

{{#invoke:params|cutting|0|2|sequential|call_for_each_value|example template}}

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 cutting modifier. For instance, the following code prints the last unnamed parameter passed, but only if at least two parameters were passed:

{{#invoke:params|sequential|cutting|1|0|cutting|-1|0|list_values}}

 Suggestion: Although {{#invoke:params|cutting|-1|1|...}} de facto gets rid of all sequential parameters, it is clearer and more idiomatic to write {{#invoke:params|non-sequential|...}} to obtain the same effect. Writing instead {{#invoke:params|sequential|cutting|-1|1|...}} will leave zero arguments to show.

with_name_matching

Modifier with_name_matching

Num. of arguments	Ad libitum
Repeatable	Yes
See also
with_name_not_matching, with_value_matching, with_value_not_matching

Brief

Discard all parameters whose name does not match any of the given patterns

Syntax

{{#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}}

Internally this modifier uses Lua's string.find() function to find whether parameter names match against given patterns; therefore, unless a target string is set to plain, please use the same syntax of Lua patterns. The plain flag can be either plain or omitted. When omitted it is assumed that the target string is a Lua pattern.

To express a logical OR the or keyword is available. To express a logical AND instead, concatenate more invocations of with_name_matching.

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

{{Infobox artery
| Name = Pulmonary artery
| Latin = truncus pulmonalis, arteria pulmonalis
| Image = {{Heart diagram 250px}}
| 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 = [[right ventricle]]
| BranchTo =
| Vein = [[pulmonary vein]]
| Precursor = truncus arteriosus
| Supplies =
}}

Test cases:

• List only the parameters whose names match against the ^Image pattern:

  ↳ {{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_matching|^Image|list}}

  ↳ |Image={{Heart diagram 250px}}|Image2=Alveoli diagram.png

• List the parameters whose names match against both patterns ^Image and %d+$:

  ↳ {{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_matching|^Image|with_name_matching|%d+$|list}}

  ↳ |Image2=Alveoli diagram.png

• List the parameters whose names match against either the ^Name or the ^Latin$ pattern:

  ↳ {{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_matching|^Name$|or|^Latin$|list}}

  ↳ |Latin=truncus pulmonalis, arteria pulmonalis|Name=Pulmonary artery

• List the parameters whose names match against either the ma plain string or the me$ pattern:

  ↳ {{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_matching|ma|plain|or|me$|list}}

  ↳ |Image={{Heart diagram 250px}}|Name=Pulmonary artery|Image2=Alveoli diagram.png

 Note: The pattern arguments passed to this function are not trimmed of their leading and trailing spaces. The or and plain keywords, and the with_name_matching function name itself, however, will be trimmed of their surrounding spaces.

with_name_not_matching

Modifier with_name_not_matching

Num. of arguments	Ad libitum
Repeatable	Yes
See also
with_name_matching, with_value_matching, with_value_not_matching

Brief

Discard all parameters whose name matches all the given patterns

Syntax

{{#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}}

Internally this modifier uses Lua's string.find() function to find whether parameter names match against given patterns; therefore, unless a target string is set to plain, please use the same syntax of Lua patterns. The plain flag can be either plain or omitted. When omitted it is assumed that the target string is a Lua pattern.

To express a logical OR the or keyword is available. To express a logical AND instead, concatenate more invocations of with_name_not_matching.

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

• List only the parameters whose names do not match against the a pattern:

  {{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_not_matching|a|list}}

  ↳ |Precursor=truncus arteriosus|Supplies=|Vein=pulmonary vein

• List the parameters whose names do not match against the a plain string and do not match against the l plain string either:

  {{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_not_matching|a|plain|with_name_not_matching|l|plain|list}}

  ↳ |Precursor=truncus arteriosus|Vein=pulmonary vein

• List the parameters whose names do not match against either the a plain string or the n plain string:

  {{#invoke:params|setting|ih/p|{{!}}|{{=}}|with_name_not_matching|a|plain|or|n|plain|list}}

  ↳ |Precursor=truncus arteriosus|Supplies=|Image={{Heart diagram 250px}}|Name=Pulmonary artery|Image2=Alveoli diagram.png|Vein=pulmonary vein

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

{{#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
}}

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

• {{#invoke:Check for unknown parameters|check}}
• {{#invoke:Check for deprecated parameters|check}}
• {{#invoke:Check for clobbered parameters|check}}
• {{#invoke:Parameter validation|validateparams}}
• {{#invoke:TemplatePar|valid}}

 Note: The pattern arguments passed to this function are not trimmed of their leading and trailing spaces. The or and plain keywords, and the with_name_not_matching function name itself, however, will be trimmed of their surrounding spaces.

with_value_matching

Modifier with_value_matching

Num. of arguments	Ad libitum
Repeatable	Yes
See also
with_name_matching, with_name_not_matching, with_value_not_matching

Brief

Discard all parameters whose value does not match any of the given patterns

Syntax

{{#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}}

Exactly like with_name_matching, but applied to parameter values instead of names.

Internally this modifier uses Lua's string.find() function to find whether parameter names match against given patterns; therefore, unless a target string is set to plain, please use the same syntax of Lua patterns. The plain flag can be either plain or omitted. When omitted it is assumed that the target string is a Lua pattern.

Example:

{{#invoke:params|with_value_matching|banana|count}}

 Note: The pattern arguments passed to this function are not trimmed of their leading and trailing spaces. The or and plain keywords, and the with_value_matching function name itself, however, will be trimmed of their surrounding spaces.

with_value_not_matching

Modifier with_value_not_matching

Num. of arguments	Ad libitum
Repeatable	Yes
See also
with_name_matching, with_name_not_matching, with_value_matching

Brief

Discard all parameters whose value matches all the given patterns

Syntax

{{#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}}

Exactly like with_name_not_matching, but applied to parameter values instead of names.

Internally this modifier uses Lua's string.find() function to find whether parameter names match against given patterns; therefore, unless a target string is set to plain, please use the same syntax of Lua patterns. The plain flag can be either plain or omitted. When omitted it is assumed that the target string is a Lua pattern.

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

{{#invoke:params|with_value_not_matching|^%s*$|setting|hi/p|{{!}}|{{=}}|list}}

 Note: The pattern arguments passed to this function are not trimmed of their leading and trailing spaces. The or and plain keywords, and the with_value_not_matching function name itself, however, will be trimmed of their surrounding spaces.

trimming_values

Modifier trimming_values

Num. of arguments	0
Repeatable	No

Brief

Remove leading and trailing spaces from values

Syntax

{{#invoke:params|trimming_values|pipe function name}}

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

Most modifiers are order-dependent, therefore placing trimming_values in different positions can generate different results. For instance, imagining our {{Example template}} being called with the following spaced arguments: {{Example template| wanna | be | my | friend | ? }}. If {{Example template}} contained the following code,

{{#invoke:params|with_value_matching|%s+$|trimming_values|setting|i/p|{{!}}|{{=}}|list}}

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

{{#invoke:params|trimming_values|with_value_matching|%s+$|setting|i/p|{{!}}|{{=}}|list}}

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 trimming_values is placed. For instance, if a template were invoked with 50 parameters and its code contained {{#invoke:params|trimming_values|cutting|-1|0|list}}, 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 {{#invoke:params|cutting|-1|0|trimming_values|list}} would first discard 49 parameters and then trim the only value left, resulting in a more efficient code. As a general rule, placing trimming_values as the last modifier is usually the best choice.

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

Using trimming_values makes this module behave like many Wikipedia modules behave. For example, if we wanted to emulate {{#invoke:Separated entries|main}}, writing

{{#invoke:params|sequential|squeezing|trimming_values|setting|i|XXXX|list_values}}

will be equivalent to writing,

{{#invoke:separated entries|main|separator=XXXX}}

whereas writing

{{#invoke:params|sequential|squeezing|trimming_values|setting|i/l|XXXX|YYYY|list_values}}

will be equivalent to writing

{{#invoke:separated entries|main|separator=XXXX|conjunction=YYYY}}

The {{./trim and call}} example template shows how to call any arbitrary template trimming all parameters beforehand.

mapping_values_by_calling

Modifier mapping_values_by_calling

Num. of arguments	Ad libitum
Repeatable	Yes
See also
mapping_values_by_invoking, mapping_values_blindly_by_calling, mapping_values_blindly_by_invoking

Brief

Map all parameter values, replacing their content with the expansion of a given template repeatedly called with at least two arguments (the parameter's name and value)

Syntax

{{#invoke:params|mapping_values_by_calling|template name|[number of additional arguments]|[argument 1]|[argument 2]|[...]|[argument N]|pipe function name}}

This modifier (temporarily) changes the contents of the parameters the current template is being called with, replacing each of them with the text returned by another template. The latter will be repeatedly called with at least two parameters: key and value. If the template name is followed by a number, this will be parsed as the amount of additional parameters to pass. For instance, before listing all parameters,

{{#invoke:params|mapping_values_by_calling|foobar|setting|i/p|{{!}}|{{=}}|list}}

will replace each value with the expansion of {{foobar|NAME|VALUE}} (where NAME and VALUE indicate each different name and value).

On the other hand,

{{#invoke:params|mapping_values_by_calling|foobar|2|hello|world|setting|i/p|{{!}}|{{=}}|list}}

will do the same, but using the expansion of {{foobar|NAME|VALUE|hello|world}}.

There are no mechanisms for passing non-sequential or non-numeric additional parameters to the mapping template. A similar function, mapping_values_blindly_by_calling, omits the first parameter (i.e. the parameter's name).

 Note: All arguments passed to this modifier except the template name and the number of additional arguments are not trimmed of their leading and trailing spaces. The mapping_values_by_calling modifier name itself, however, will be trimmed of its surrounding spaces.

mapping_values_by_invoking

Modifier mapping_values_by_invoking

Num. of arguments	Ad libitum
Repeatable	Yes
See also
mapping_values_by_calling, mapping_values_blindly_by_calling, mapping_values_blindly_by_invoking

Brief

Map all parameter values, replacing their content with the text returned by a given module function repeatedly invoked with at least two arguments (the parameter's name and value)

Syntax

{{#invoke:params|mapping_values_by_invoking|template name|[number of additional arguments]|[argument 1]|[argument 2]|[...]|[argument N]|pipe function name}}

This modifier (temporarily) changes the contents of the parameters the current template is being called with, replacing each of them with text returned by a custom module function. The latter will be repeatedly invoked with at least two arguments: key and value. If the function name is followed by a number, this will be parsed as the amount of additional arguments to pass. For instance, before listing all parameters,

{{#invoke:params|mapping_values_by_invoking|foobar|main|setting|i/p|{{!}}|{{=}}|list}}

will replace each value with the expansion of {{#invoke:foobar|main|NAME|VALUE}} (where NAME and VALUE indicate each different name and value).

On the other hand,

{{#invoke:params|mapping_values_by_invoking|foobar|main|2|hello|world|setting|i/p|{{!}}|{{=}}|list}}

will do the same, but using the expansion of {{#invoke:foobar|main|NAME|VALUE|hello|world}}.

There are no mechanisms for passing non-sequential or non-numeric additional arguments to the mapping module. A similar function, mapping_values_blindly_by_invoking, omits the first argument (i.e. the parameter's name).

 Note: All arguments passed to this modifier except the module name, the function name and the number of additional arguments are not trimmed of their leading and trailing spaces. The mapping_values_by_invoking modifier name itself, however, will be trimmed of its surrounding spaces.

mapping_values_blindly_by_calling

Modifier mapping_values_blindly_by_calling

Num. of arguments	Ad libitum
Repeatable	Yes
See also
mapping_values_by_calling, mapping_values_by_invoking, mapping_values_blindly_by_invoking

Brief

Map all parameter values, replacing their content with the expansion of a given template repeatedly called with at least one argument (the parameter's value)

Syntax

{{#invoke:params|mapping_values_blindly_by_calling|template name|[number of additional arguments]|[argument 1]|[argument 2]|[...]|[argument N]|pipe function name}}

This modifier (temporarily) changes the contents of the parameters the current template is being called with, replacing each of them with the text returned by another template. The latter will be repeatedly called with at least one parameter: the parameter's value. If the template name is followed by a number, this will be parsed as the amount of additional parameters to pass. For instance, before listing all parameters,

{{#invoke:params|mapping_values_blindly_by_calling|foobar|setting|i/p|{{!}}|{{=}}|list}}

will replace each value with the expansion of {{foobar|VALUE}} (where VALUE indicates each different value).

On the other hand,

{{#invoke:params|mapping_values_blindly_by_calling|foobar|2|hello|world|setting|i/p|{{!}}|{{=}}|list}}

will do the same, but using the expansion of {{foobar|VALUE|hello|world}}.

There are no mechanisms for passing non-sequential or non-numeric additional parameters to the mapping template. A similar function, mapping_values_by_calling, passes the parameter's name as well, as first argument.

 Note: All arguments passed to this modifier except the template name and the number of additional arguments are not trimmed of their leading and trailing spaces. The mapping_values_blindly_by_calling modifier name itself, however, will be trimmed of its surrounding spaces.

mapping_values_blindly_by_invoking

Modifier mapping_values_blindly_by_invoking

Num. of arguments	Ad libitum
Repeatable	Yes
See also
mapping_values_by_calling, mapping_values_by_invoking, mapping_values_blindly_by_calling

Brief

Map all parameter values, replacing their content with the text returned by a given module function repeatedly invoked with at least one argument (the parameter's value)

Syntax

{{#invoke:params|mapping_values_blindly_by_invoking|template name|[number of additional arguments]|[argument 1]|[argument 2]|[...]|[argument N]|pipe function name}}

This modifier (temporarily) changes the contents of the parameters the current template is being called with, replacing each of them with text returned by a custom module function. The latter will be repeatedly invoked with at least one argument: the parameter's value. If the function name is followed by a number, this will be parsed as the amount of additional arguments to pass. For instance, before listing all parameters,

{{#invoke:params|mapping_values_blindly_by_invoking|foobar|main|setting|i/p|{{!}}|{{=}}|list}}

will replace each value with the expansion of {{#invoke:foobar|main|VALUE}} (where VALUE indicates each different value).

On the other hand,

{{#invoke:params|mapping_values_blindly_by_invoking|foobar|main|2|hello|world|setting|i/p|{{!}}|{{=}}|list}}

will do the same, but using the expansion of {{#invoke:foobar|main|VALUE|hello|world}}.

There are no mechanisms for passing non-sequential or non-numeric additional arguments to the mapping module. A similar function, mapping_values_by_invoking, passes the parameter's name as well, as first argument.

 Note: All arguments passed to this modifier except the module name, the function name and the number of additional arguments are not trimmed of their leading and trailing spaces. The mapping_values_blindly_by_invoking modifier name itself, however, will be trimmed of its surrounding spaces.

Subpages

• en:Module:Params/ChangeLog – Record of the most important changes in the module's code
• en:Module:Params/testcases – Testing the module's capabilities

See also

• {{#invoke:TemplatePar}}
• {{#invoke:ParameterCount}}
• {{#invoke:Separated entries|main}}
• {{#invoke:Enumerate|main}}
• {{#invoke:Check for unknown parameters|check}}
• {{#invoke:Check for deprecated parameters|check}}
• {{#invoke:Check for clobbered parameters|check}}
• {{#invoke:Parameter validation}}
• {{#invoke:Expand wikitext|main}}
• {{#invoke:For loop|main}} and {{For loop}}
• {{#invoke:For nowiki|main}} and {{For nowiki}}
• Project:TemplateData