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Module:Arguments/doc: Difference between revisions

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<noinclude><!--
-->{{#ifeq:{{SUBPAGENAME}}|doc||{{Documentation subpage}}}}<!--
--><languages /><!--
--></noinclude>{{#switch:<translate></translate>
| =
<includeonly>{{Languages|Module:Arguments/doc}}</includeonly>
<!-- Add categories where indicated at the bottom of this page and interwikis at Wikidata -->
{{Shared Template Warning|Module:Arguments|Module:Arguments}}
{{Used in system}}
{{Used in system}}
{{Module rating|release}}
{{Module rating|p}}
{{Module rating|protected}}


<translate><!--T:1--> This module provides easy processing of arguments passed from <tvar name=1>{{Magic word|#invoke|...|ext=Scribunto|code=1|nowrap=1}}</tvar>.</translate>
This module provides easy processing of arguments passed from <code>#invoke</code>. It is a meta-module, meant for use by other modules, and should not be called from <code>#invoke</code> directly (for a module directly invocable by templates you might want to have a look at {{ml|params|}}). Its features include:
<translate><!--T:2--> It is a meta-module, meant for use by other modules, and should not be called from <tvar name=1>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar> directly.</translate>
* Easy trimming of arguments and removal of blank arguments.
<translate><!--T:3--> Its features include:</translate>
* Arguments can be passed by both the current frame and by the parent frame at the same time. (More details below.)
* Arguments can be passed in directly from another Lua module or from the debug console.
* Most features can be customized.


* <translate><!--T:4--> Easy trimming of arguments and removal of blank arguments.</translate>
== Basic use ==
* <translate><!--T:5--> Arguments can be passed by both the current frame and by the parent frame at the same time.</translate> <translate><!--T:6--> (More details below.)</translate>
* <translate><!--T:7--> Arguments can be passed in directly from another Lua module or from the debug console.</translate>
* <translate><!--T:8--> Arguments are fetched as needed, which can help avoid (some) problems with <tvar name=1>{{xtag|ref}}</tvar> tags.</translate>
* <translate><!--T:9--> Most features can be customized.</translate>


<translate>
First, you need to load the module. It contains one function, named <code>getArgs</code>.
== Basic use == <!--T:10-->
</translate>
<translate><!--T:11--> First, you need to load the module.</translate>
<translate><!--T:12--> It contains one function, named <tvar name=1><code>getArgs</code></tvar>.</translate>


<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
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</syntaxhighlight>
</syntaxhighlight>


<translate><!--T:13--> In the most basic scenario, you can use <tvar name=1><code>getArgs</code></tvar> inside your main function.</translate>
In the most basic scenario, you can use getArgs inside your main function. The variable <code>args</code> is a table containing the arguments from #invoke. (See below for details.)
<translate><!--T:14--> The variable <tvar name=1><code>args</code></tvar> is a table containing the arguments from <tvar name=2>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar>.</translate>
<translate><!--T:15--> (See below for details.)</translate>


<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
Line 41: Line 24:
function p.main(frame)
function p.main(frame)
local args = getArgs(frame)
local args = getArgs(frame)
-- <translate nowrap><!--T:16--> Main module code goes here.</translate>
-- Main module code goes here.
end
end


Line 47: Line 30:
</syntaxhighlight>
</syntaxhighlight>


<translate><!--T:17--> However, the recommended practice is to use a function just for processing arguments from <tvar name=1>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar>.</translate>
=== Recommended practice ===
<translate><!--T:18--> This means that if someone calls your module from another Lua module you don't have to have a frame object available, which improves performance.</translate>
However, the recommended practice is to use a function just for processing arguments from #invoke. This means that if someone calls your module from another Lua module you don't have to have a frame object available, which improves performance.


<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
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function p._main(args)
function p._main(args)
-- <translate nowrap><!--T:19--> Main module code goes here.</translate>
-- Main module code goes here.
end
end


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</syntaxhighlight>
</syntaxhighlight>


<translate>
The way this is called from a template is <code><nowiki>{{#invoke:Example|main}}</nowiki></code> (optionally with some parameters like <code><nowiki>{{#invoke:Example|main|arg1=value1|arg2=value2}}</nowiki></code>), and the way this is called from a module is <syntaxhighlight lang=lua inline>require('Module:Example')._main({arg1 = 'value1', arg2 = value2, 'spaced arg3' = 'value3'})</syntaxhighlight>. What this second one does is construct a table with the arguments in it, then gives that table to the p._main(args) function, which uses it natively.
<!--T:20-->
 
If you want multiple functions to use the arguments, and you also want them to be accessible from <tvar name=1>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar>, you can use a wrapper function.
=== Multiple functions ===
</translate>
If you want multiple functions to use the arguments, and you also want them to be accessible from #invoke, you can use a wrapper function.


<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
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function p._func1(args)
function p._func1(args)
-- <translate nowrap><!--T:21--> Code for the first function goes here.</translate>
-- Code for the first function goes here.
end
end


Line 92: Line 75:


function p._func2(args)
function p._func2(args)
-- <translate nowrap><!--T:22--> Code for the second function goes here.</translate>
-- Code for the second function goes here.
end
end


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</syntaxhighlight>
</syntaxhighlight>


<translate>
=== Options ===
=== Options === <!--T:23-->
 
</translate>
The following options are available. They are explained in the sections below.
<translate><!--T:24--> The following options are available.</translate>
<translate><!--T:25--> They are explained in the sections below.</translate>


<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
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removeBlanks = false,
removeBlanks = false,
valueFunc = function (key, value)
valueFunc = function (key, value)
-- <translate nowrap><!--T:26--> Code for processing one argument</translate>
-- Code for processing one argument
end,
end,
frameOnly = true,
frameOnly = true,
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</syntaxhighlight>
</syntaxhighlight>


<translate>
=== Trimming and removing blanks ===
=== Trimming and removing blanks === <!--T:27-->
 
</translate>
Blank arguments often trip up coders new to converting MediaWiki templates to Lua. In template syntax, blank strings and strings consisting only of whitespace are considered false. However, in Lua, blank strings and strings consisting of whitespace are considered true. This means that if you don't pay attention to such arguments when you write your Lua modules, you might treat something as true that should actually be treated as false. To avoid this, by default this module removes all blank arguments.
<translate><!--T:28--> Blank arguments often trip up coders new to converting MediaWiki templates to Lua.</translate>
<translate><!--T:29--> In template syntax, blank strings and strings consisting only of whitespace are considered <tvar name=1><code>false</code></tvar>.</translate>
<translate><!--T:30--> However, in Lua, blank strings and strings consisting of whitespace are considered <tvar name=1><code>true</code></tvar>.</translate>
<translate><!--T:31--> This means that if you don't pay attention to such arguments when you write your Lua modules, you might treat something as <tvar name=1><code>true</code></tvar> that should actually be treated as <tvar name=2><code>false</code></tvar>.</translate>
<translate><!--T:32--> To avoid this, by default this module removes all blank arguments.</translate>


<translate><!--T:33--> Similarly, whitespace can cause problems when dealing with positional arguments.</translate>
Similarly, whitespace can cause problems when dealing with positional arguments. Although whitespace is trimmed for named arguments coming from #invoke, it is preserved for positional arguments. Most of the time this additional whitespace is not desired, so this module trims it off by default.
<translate><!--T:34--> Although whitespace is trimmed for named arguments coming from <tvar name=1>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar>, it is preserved for positional arguments.</translate>
<translate><!--T:35--> Most of the time this additional whitespace is not desired, so this module trims it off by default.</translate>


<translate><!--T:36--> However, sometimes you want to use blank arguments as input, and sometimes you want to keep additional whitespace.</translate>
However, sometimes you want to use blank arguments as input, and sometimes you want to keep additional whitespace. This can be necessary to convert some templates exactly as they were written. If you want to do this, you can set the <code>trim</code> and <code>removeBlanks</code> arguments to <code>false</code>.
<translate><!--T:37--> This can be necessary to convert some templates exactly as they were written.</translate>
<translate><!--T:38--> If you want to do this, you can set the <tvar name=1><code>trim</code></tvar> and <tvar name=2><code>removeBlanks</code></tvar> arguments to <tvar name=3><code>false</code></tvar>.</translate>


<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
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</syntaxhighlight>
</syntaxhighlight>


<translate>
=== Custom formatting of arguments ===
=== Custom formatting of arguments === <!--T:39-->
</translate>
<translate><!--T:40--> Sometimes you want to remove some blank arguments but not others, or perhaps you might want to put all of the positional arguments in lower case.</translate>
<translate><!--T:41--> To do things like this you can use the <tvar name=1><code>valueFunc</code></tvar> option.</translate>
<translate><!--T:42--> The input to this option must be a function that takes two parameters, <tvar name=1><code>key</code></tvar> and <tvar name=2><code>value</code></tvar>, and returns a single value.</translate>
<translate><!--T:43--> This value is what you will get when you access the field <tvar name=1><code>key</code></tvar> in the <tvar name=2><code>args</code></tvar> table.</translate>


'''<translate><!--T:44--> Example 1:</translate>'''
Sometimes you want to remove some blank arguments but not others, or perhaps you might want to put all of the positional arguments in lower case. To do things like this you can use the <code>valueFunc</code> option. The input to this option must be a function that takes two parameters, <code>key</code> and <code>value</code>, and returns a single value. This value is what you will get when you access the field <code>key</code> in the <code>args</code> table.
<translate><!--T:45--> This function preserves whitespace for the first positional argument, but trims all other arguments and removes all other blank arguments.</translate>


Example 1: this function preserves whitespace for the first positional argument's value, but trims all other arguments' value and removes all other blank arguments.
<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
local args = getArgs(frame, {
local args = getArgs(frame, {
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</syntaxhighlight>
</syntaxhighlight>


'''<translate><!--T:46--> Example 2:</translate>'''
Example 2: this function removes blank arguments and converts all argument values to lower case, but doesn't trim whitespace from positional parameters.
<translate><!--T:47--> This function removes blank arguments and converts all arguments to lower case, but doesn't trim whitespace from positional parameters.</translate>
 
<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
local args = getArgs(frame, {
local args = getArgs(frame, {
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</syntaxhighlight>
</syntaxhighlight>


{{Note|text=
Note: the above functions will fail if passed input that is not of type <code>string</code> or <code>nil</code>. This might be the case if you use the <code>getArgs</code> function in the main function of your module, and that function is called by another Lua module. In this case, you will need to check the type of your input. This is not a problem if you are using a function specially for arguments from #invoke (i.e. you have <code>p.main</code> and <code>p._main</code> functions, or something similar).
<translate><!--T:48--> The above functions will fail if passed input that is not of type <tvar name=1><code>string</code></tvar> or <tvar name=2><code>nil</code></tvar>.</translate>
<translate><!--T:49--> This might be the case if you use the <tvar name=1><code>getArgs</code></tvar> function in the main function of your module, and that function is called by another Lua module.</translate>
<translate><!--T:50--> In this case, you will need to check the type of your input.</translate>
<translate><!--T:51--> This is not a problem if you are using a function specially for arguments from <tvar name=1>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar> (i.e. you have <tvar name=2><code>p.main</code></tvar> and <tvar name=3><code>p._main</code></tvar> functions, or something similar).</translate>
}}


{{Collapse top|1=<translate><!--T:52--> Examples 1 and 2 with type checking</translate>}}
{{cot|Examples 1 and 2 with type checking}}
<translate>
<!--T:53-->
Example 1:
Example 1:
</translate>
<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
local args = getArgs(frame, {
local args = getArgs(frame, {
Line 223: Line 179:
</syntaxhighlight>
</syntaxhighlight>


<translate>
<!--T:54-->
Example 2:
Example 2:
</translate>
<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
local args = getArgs(frame, {
local args = getArgs(frame, {
Line 243: Line 196:
})
})
</syntaxhighlight>
</syntaxhighlight>
{{Collapse bottom}}
{{cob}}


<translate>
Also, please note that the <code>valueFunc</code> function is called more or less every time an argument is requested from the <code>args</code> table, so if you care about performance you should make sure you aren't doing anything inefficient with your code.
<!--T:55-->
Also, please note that the <tvar name=1><code>valueFunc</code></tvar> function is called more or less every time an argument is requested from the <tvar name=2><code>args</code></tvar> table, so if you care about performance you should make sure you aren't doing anything inefficient with your code.


=== Frames and parent frames === <!--T:56-->
=== Frames and parent frames ===
</translate>


<translate><!--T:57--> Arguments in the <tvar name=1><code>args</code></tvar> table can be passed from the current frame or from its parent frame at the same time.</translate>
Arguments in the <code>args</code> table can be passed from the current frame or from its parent frame at the same time. To understand what this means, it is easiest to give an example. Let's say that we have a module called <code>Module:ExampleArgs</code>. This module prints the first two positional arguments that it is passed.
<translate><!--T:58--> To understand what this means, it is easiest to give an example.</translate>
<translate><!--T:59--> Let's say that we have a module called <tvar name=1><code>Module:ExampleArgs</code></tvar>.</translate>
<translate><!--T:60--> This module prints the first two positional arguments that it is passed.</translate>


{{Collapse top|1=<translate><!--T:61--> <tvar name=1>Module:ExampleArgs</tvar> code</translate>}}
{{cot|Module:ExampleArgs code}}
<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
local getArgs = require('Module:Arguments').getArgs
local getArgs = require('Module:Arguments').getArgs
Line 275: Line 222:
return p
return p
</syntaxhighlight>
</syntaxhighlight>
{{Collapse bottom}}
{{cob}}


<translate><!--T:62--> <tvar name=1><code>Module:ExampleArgs</code></tvar> is then called by <tvar name=2><code>Template:ExampleArgs</code></tvar>, which contains the code <tvar name=3><code><nowiki>{{#invoke:ExampleArgs|main|firstInvokeArg}}</nowiki></code></tvar>.</translate>
<code>Module:ExampleArgs</code> is then called by <code>Template:ExampleArgs</code>, which contains the code <code><nowiki>{{#invoke:ExampleArgs|main|firstInvokeArg}}</nowiki></code>. This produces the result "firstInvokeArg".
<translate><!--T:63--> This produces the result <tvar name=1>"firstInvokeArg"</tvar>.</translate>


<translate>
Now if we were to call <code>Template:ExampleArgs</code>, the following would happen:
<!--T:64-->
Now if we were to call <tvar name=1><code>Template:ExampleArgs</code></tvar>, the following would happen:
</translate>


{{(!}} class="wikitable" style="width: 50em; max-width: 100%;"
{| class="wikitable" style="width: 50em; max-width: 100%;"
{{!}}-
|-
! style="width: 60%;" {{!}} <translate><!--T:65--> Code</translate>
! style="width: 60%;" | Code
! style="width: 40%;" {{!}} <translate><!--T:66--> Result</translate>
! style="width: 40%;" | Result
{{!}}-
|-
{{!}} <code><nowiki>{{ExampleArgs}}</nowiki></code>
| <code><nowiki>{{ExampleArgs}}</nowiki></code>
{{!}} firstInvokeArg
| firstInvokeArg
{{!}}-
|-
{{!}} <code><nowiki>{{ExampleArgs|firstTemplateArg}}</nowiki></code>
| <code><nowiki>{{ExampleArgs|firstTemplateArg}}</nowiki></code>
{{!}} firstInvokeArg
| firstInvokeArg
{{!}}-
|-
{{!}} <code><nowiki>{{ExampleArgs|firstTemplateArg|secondTemplateArg}}</nowiki></code>
| <code><nowiki>{{ExampleArgs|firstTemplateArg|secondTemplateArg}}</nowiki></code>
{{!}} firstInvokeArg secondTemplateArg
| firstInvokeArg secondTemplateArg
{{!)}}
|}


<translate><!--T:67--> There are three options you can set to change this behaviour: <tvar name=1><code>frameOnly</code></tvar>, <tvar name=2><code>parentOnly</code></tvar> and <tvar name=3><code>parentFirst</code></tvar>.</translate>
There are three options you can set to change this behaviour: <code>frameOnly</code>, <code>parentOnly</code> and <code>parentFirst</code>. If you set <code>frameOnly</code> then only arguments passed from the current frame will be accepted; if you set <code>parentOnly</code> then only arguments passed from the parent frame will be accepted; and if you set <code>parentFirst</code> then arguments will be passed from both the current and parent frames, but the parent frame will have priority over the current frame. Here are the results in terms of <code>Template:ExampleArgs</code>:
<translate><!--T:68--> If you set <tvar name=1><code>frameOnly</code></tvar> then only arguments passed from the current frame will be accepted; if you set <tvar name=2><code>parentOnly</code></tvar> then only arguments passed from the parent frame will be accepted; and if you set <tvar name=3><code>parentFirst</code></tvar> then arguments will be passed from both the current and parent frames, but the parent frame will have priority over the current frame.</translate>
<translate><!--T:69--> Here are the results in terms of <tvar name=1><code>Template:ExampleArgs</code></tvar>:</translate>


<dl>
; frameOnly
<dt><code>frameOnly</code></dt>
{| class="wikitable" style="width: 50em; max-width: 100%;"
<dd>
|-
{{(!}} class="wikitable" style="width: 50em; max-width: 100%;"
! style="width: 60%;" | Code
{{!}}-
! style="width: 40%;" | Result
! style="width: 60%;" {{!}} <translate><!--T:70--> Code</translate>
|-
! style="width: 40%;" {{!}} <translate><!--T:71--> Result</translate>
| <code><nowiki>{{ExampleArgs}}</nowiki></code>
{{!}}-
| firstInvokeArg
{{!}} <code><nowiki>{{ExampleArgs}}</nowiki></code>
|-
{{!}} firstInvokeArg
| <code><nowiki>{{ExampleArgs|firstTemplateArg}}</nowiki></code>
{{!}}-
| firstInvokeArg
{{!}} <code><nowiki>{{ExampleArgs|firstTemplateArg}}</nowiki></code>
|-
{{!}} firstInvokeArg
| <code><nowiki>{{ExampleArgs|firstTemplateArg|secondTemplateArg}}</nowiki></code>
{{!}}-
| firstInvokeArg
{{!}} <code><nowiki>{{ExampleArgs|firstTemplateArg|secondTemplateArg}}</nowiki></code>
|}
{{!}} firstInvokeArg
{{!)}}
</dd>


<dt><code>parentOnly</code></dt>
; parentOnly
<dd>
{| class="wikitable" style="width: 50em; max-width: 100%;"
{{(!}} class="wikitable" style="width: 50em; max-width: 100%;"
|-
{{!}}-
! style="width: 60%;" | Code
! style="width: 60%;" {{!}} <translate><!--T:72--> Code</translate>
! style="width: 40%;" | Result
! style="width: 40%;" {{!}} <translate><!--T:73--> Result</translate>
|-
{{!}}-
| <code><nowiki>{{ExampleArgs}}</nowiki></code>
{{!}} <code><nowiki>{{ExampleArgs}}</nowiki></code>
|
{{!}}
|-
{{!}}-
| <code><nowiki>{{ExampleArgs|firstTemplateArg}}</nowiki></code>
{{!}} <code><nowiki>{{ExampleArgs|firstTemplateArg}}</nowiki></code>
| firstTemplateArg
{{!}} firstTemplateArg
|-
{{!}}-
| <code><nowiki>{{ExampleArgs|firstTemplateArg|secondTemplateArg}}</nowiki></code>
{{!}} <code><nowiki>{{ExampleArgs|firstTemplateArg|secondTemplateArg}}</nowiki></code>
| firstTemplateArg secondTemplateArg
{{!}} firstTemplateArg secondTemplateArg
|}
{{!)}}
</dd>


<dt><code>parentFirst</code></dt>
; parentFirst
<dd>
{| class="wikitable" style="width: 50em; max-width: 100%;"
{{(!}} class="wikitable" style="width: 50em; max-width: 100%;"
|-
{{!}}-
! style="width: 60%;" | Code
! style="width: 60%;" {{!}} <translate><!--T:74--> Code</translate>
! style="width: 40%;" | Result
! style="width: 40%;" {{!}} <translate><!--T:75--> Result</translate>
|-
{{!}}-
| <code><nowiki>{{ExampleArgs}}</nowiki></code>
{{!}} <code><nowiki>{{ExampleArgs}}</nowiki></code>
| firstInvokeArg
{{!}} firstInvokeArg
|-
{{!}}-
| <code><nowiki>{{ExampleArgs|firstTemplateArg}}</nowiki></code>
{{!}} <code><nowiki>{{ExampleArgs|firstTemplateArg}}</nowiki></code>
| firstTemplateArg
{{!}} firstTemplateArg
|-
{{!}}-
| <code><nowiki>{{ExampleArgs|firstTemplateArg|secondTemplateArg}}</nowiki></code>
{{!}} <code><nowiki>{{ExampleArgs|firstTemplateArg|secondTemplateArg}}</nowiki></code>
| firstTemplateArg secondTemplateArg
{{!}} firstTemplateArg secondTemplateArg
|}
{{!)}}
</dd>
</dl>


{{Note|text=
Notes:
{{Ordered list
# If you set both the <code>frameOnly</code> and <code>parentOnly</code> options, the module won't fetch any arguments at all from #invoke. This is probably not what you want.
|1=
# In some situations a parent frame may not be available, e.g. if getArgs is passed the parent frame rather than the current frame. In this case, only the frame arguments will be used (unless parentOnly is set, in which case no arguments will be used) and the <code>parentFirst</code> and <code>frameOnly</code> options will have no effect.
<translate><!--T:76--> If you set both the <tvar name=1><code>frameOnly</code></tvar> and <tvar name=2><code>parentOnly</code></tvar> options, the module won't fetch any arguments at all from <tvar name=3>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar>.</translate>
<translate><!--T:77--> This is probably not what you want.</translate>
|2=
<translate><!--T:78--> In some situations a parent frame may not be available, e.g. if <tvar name=1><code>getArgs</code></tvar> is passed the parent frame rather than the current frame.</translate>
<translate><!--T:79--> In this case, only the frame arguments will be used (unless <tvar name=1><code>parentOnly</code></tvar> is set, in which case no arguments will be used) and the <tvar name=2><code>parentFirst</code></tvar> and <tvar name=3><code>frameOnly</code></tvar> options will have no effect.</translate>
}}
}}


<translate>
=== Wrappers ===
=== Wrappers === <!--T:80-->
</translate>


<translate><!--T:81--> The <tvar name=1><code>wrappers</code></tvar> option is used to specify a limited number of templates as ''wrapper templates'', that is, templates whose only purpose is to call a module.</translate>
The ''wrappers'' option is used to specify a limited number of templates as ''wrapper templates'', that is, templates whose only purpose is to call a module. If the module detects that it is being called from a wrapper template, it will only check for arguments in the parent frame; otherwise it will only check for arguments in the frame passed to getArgs. This allows modules to be called by either #invoke or through a wrapper template without the loss of performance associated with having to check both the frame and the parent frame for each argument lookup.
<translate><!--T:82--> If the module detects that it is being called from a wrapper template, it will only check for arguments in the parent frame; otherwise it will only check for arguments in the frame passed to <tvar name=1><code>getArgs</code></tvar>.</translate>
<translate><!--T:83--> This allows modules to be called by either <tvar name=1>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar> or through a wrapper template without the loss of performance associated with having to check both the frame and the parent frame for each argument lookup.</translate>


<translate><!--T:84--> For example, the only content of <tvar name=1>{{tlx|Navbox}}</tvar> (excluding content in <tvar name=2>{{tag|noinclude}}</tvar> tags) is <tvar name=3><code><nowiki>{{#invoke:Navbox|navbox}}</nowiki></code></tvar>.</translate>
For example, the only content of [[Template:Side box]] (excluding content in {{tag|noinclude}} tags) is <code><nowiki>{{#invoke:Side box|main}}</nowiki></code>. There is no point in checking the arguments passed directly to the #invoke statement for this template, as no arguments will ever be specified there. We can avoid checking arguments passed to #invoke by using the ''parentOnly'' option, but if we do this then #invoke will not work from other pages either. If this were the case, the {{para|text|Some text}} in the code <code><nowiki>{{#invoke:Side box|main|text=Some text}}</nowiki></code> would be ignored completely, no matter what page it was used from. By using the <code>wrappers</code> option to specify 'Template:Side box' as a wrapper, we can make <code><nowiki>{{#invoke:Side box|main|text=Some text}}</nowiki></code> work from most pages, while still not requiring that the module check for arguments on the [[Template:Side box]] page itself.
<translate><!--T:85--> There is no point in checking the arguments passed directly to the <tvar name=1>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar> statement for this template, as no arguments will ever be specified there.</translate>
<translate><!--T:86--> We can avoid checking arguments passed to <tvar name=1>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar> by using the <tvar name=2><code>parentOnly</code></tvar> option, but if we do this then <tvar name=1>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar> will not work from other pages either.</translate>
<translate><!--T:87--> If this were the case, then {{<tvar name=1>tmpl|0={{para|text|$1}}</tvar>|Some text}} in the code {{<tvar name=2>tmpl|0={{tlc|<nowiki>#invoke:Navbox</nowiki>|navbox|3=text=$1}}</tvar>|Some text}} would be ignored completely, no matter what page it was used from.</translate>
<translate><!--T:88--> By using the <tvar name=1><code>wrappers</code></tvar> option to specify <tvar name=2>[[Template:Navbox]]</tvar> as a wrapper, we can make {{<tvar name=3>tmpl|0={{tlc|<nowiki>#invoke:Navbox</nowiki>|main|3=text=$1}}</tvar>|Some text}} work from most pages, while still not requiring that the module check for arguments on the <tvar name=2>[[Template:Navbox]]</tvar> page itself.</translate>


<translate>
<!--T:89-->
Wrappers can be specified either as a string, or as an array of strings.
Wrappers can be specified either as a string, or as an array of strings.
</translate>


<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
Line 395: Line 310:
})
})
</syntaxhighlight>
</syntaxhighlight>


<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
Line 401: Line 317:
'Template:Wrapper 1',
'Template:Wrapper 1',
'Template:Wrapper 2',
'Template:Wrapper 2',
-- <translate nowrap><!--T:90--> Any number of wrapper templates can be added here.</translate>
-- Any number of wrapper templates can be added here.
}
}
})
})
</syntaxhighlight>
</syntaxhighlight>


{{Note|text=
Notes:
{{Ordered list
# The module will automatically detect if it is being called from a wrapper template's /sandbox subpage, so there is no need to specify sandbox pages explicitly.
|1=
# The ''wrappers'' option effectively changes the default of the ''frameOnly'' and ''parentOnly'' options. If, for example, ''parentOnly'' were explicitly set to 0 with ''wrappers'' set, calls via wrapper templates would result in both frame and parent arguments being loaded, though calls not via wrapper templates would result in only frame arguments being loaded.
<translate><!--T:91--> The module will automatically detect if it is being called from a wrapper template's <tvar name=1><code>/sandbox</code></tvar> subpage, so there is no need to specify sandbox pages explicitly.</translate>
# If the ''wrappers'' option is set and no parent frame is available, the module will always get the arguments from the frame passed to <code>getArgs</code>.
|2=
 
<translate><!--T:92--> The <tvar name=1><code>wrappers</code></tvar> option effectively changes the default of the <tvar name=2><code>frameOnly</code></tvar> and <tvar name=3><code>parentOnly</code></tvar> options.</translate>
=== Writing to the args table ===
<translate><!--T:93--> If, for example, <tvar name=1><code>parentOnly</code></tvar> were explicitly set to <tvar name=2><code>false</code></tvar> with <tvar name=3><code>wrappers</code></tvar> set, calls via wrapper templates would result in both frame and parent arguments being loaded, though calls not via wrapper templates would result in only frame arguments being loaded.</translate>
|3=
<translate><!--T:94--> If the <tvar name=1><code>wrappers</code></tvar> option is set and no parent frame is available, the module will always get the arguments from the frame passed to <tvar name=2><code>getArgs</code></tvar>.</translate>
}}
}}


<translate>
Sometimes it can be useful to write new values to the args table. This is possible with the default settings of this module. (However, bear in mind that it is usually better coding style to create a new table with your new values and copy arguments from the args table as needed.)
=== Writing to the <tvar name=1><code>args</code></tvar> table === <!--T:95-->
</translate>
<translate><!--T:96--> Sometimes it can be useful to write new values to the <tvar name=1><code>args</code></tvar> table.</translate>
<translate><!--T:97--> This is possible with the default settings of this module.</translate>
<translate><!--T:98--> (However, bear in mind that it is usually better coding style to create a new table with your new values and copy arguments from the <tvar name=1><code>args</code></tvar> table as needed.)</translate>


<syntaxhighlight lang="lua">
<syntaxhighlight lang="lua">
args.foo = '<translate nowrap><!--T:99--> some value</translate>'
args.foo = 'some value'
</syntaxhighlight>
</syntaxhighlight>


<translate><!--T:100--> It is possible to alter this behaviour with the <tvar name=1><code>readOnly</code></tvar> and <tvar name=2><code>noOverwrite</code></tvar> options.</translate>
It is possible to alter this behaviour with the <code>readOnly</code> and <code>noOverwrite</code> options. If <code>readOnly</code> is set then it is not possible to write any values to the args table at all. If <code>noOverwrite</code> is set, then it is possible to add new values to the table, but it is not possible to add a value if it would overwrite any arguments that are passed from #invoke.
<translate><!--T:101--> If <tvar name=1><code>readOnly</code></tvar> is set then it is not possible to write any values to the <tvar name=2><code>args</code></tvar> table at all.</translate>
 
<translate><!--T:102--> If <tvar name=1><code>noOverwrite</code></tvar> is set, then it is possible to add new values to the table, but it is not possible to add a value if it would overwrite any arguments that are passed from <tvar name=2>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar>.</translate>
=== Ref tags ===
 
This module uses [[mw:Extension:Scribunto/Lua reference manual#Metatables|metatables]] to fetch arguments from #invoke. This allows access to both the frame arguments and the parent frame arguments without using the <code>pairs()</code> function. This can help if your module might be passed {{tag|ref}} tags as input.


<translate>
As soon as {{tag|ref}} tags are accessed from Lua, they are processed by the MediaWiki software and the reference will appear in the reference list at the bottom of the article. If your module proceeds to omit the reference tag from the output, you will end up with a phantom reference – a reference that appears in the reference list but without any number linking to it. This has been a problem with modules that use <code>pairs()</code> to detect whether to use the arguments from the frame or the parent frame, as those modules automatically process every available argument.
=== Ref tags === <!--T:103-->
</translate>
<translate><!--T:104--> This module uses [[<tvar name=1>mw:Special:MyLanguage/Extension:Scribunto/Lua reference manual#Metatables</tvar>|metatables]] to fetch arguments from <tvar name=2>{{tlc|<nowiki>#invoke:...</nowiki>}}</tvar>.</translate>
<translate><!--T:105--> This allows access to both the frame arguments and the parent frame arguments without using the <tvar name=1><code>pairs()</code></tvar> function.</translate>
<translate><!--T:106--> This can help if your module might be passed <tvar name=1>{{xtag|ref}}</tvar> tags as input.</translate>


<translate><!--T:107--> As soon as <tvar name=1>{{xtag|ref}}</tvar> tags are accessed from Lua, they are processed by the MediaWiki software and the reference will appear in the reference list at the bottom of the article.</translate>
This module solves this problem by allowing access to both frame and parent frame arguments, while still only fetching those arguments when it is necessary. The problem will still occur if you use <code>pairs(args)</code> elsewhere in your module, however.
<translate><!--T:108--> If your module proceeds to omit the reference tag from the output, you will end up with a phantom reference - a reference that appears in the reference list, but no number that links to it.</translate>
<translate><!--T:109--> This has been a problem with modules that use <tvar name=1><code>pairs()</code></tvar> to detect whether to use the arguments from the frame or the parent frame, as those modules automatically process every available argument.</translate>


<translate><!--T:110--> This module solves this problem by allowing access to both frame and parent frame arguments, while still only fetching those arguments when it is necessary.</translate>
=== Known limitations ===
<translate><!--T:111--> The problem will still occur if you use <tvar name=1><code>pairs(args)</code></tvar> elsewhere in your module, however.</translate>


<translate>
The use of metatables also has its downsides. Most of the normal Lua table tools won't work properly on the args table, including the <code>#</code> operator, the <code>next()</code> function, and the functions in the table library. If using these is important for your module, you should use your own argument processing function instead of this module.<includeonly>{{#ifeq:{{SUBPAGENAME}}|sandbox||
=== Known limitations === <!--T:112-->
[[Category:Lua metamodules]]
</translate>
}}</includeonly>
<translate><!--T:113--> The use of metatables also has its downsides.</translate>
<translate><!--T:114--> Most of the normal Lua table tools won't work properly on the <tvar name=4><code>args</code></tvar> table, including the <tvar name=1><code>#</code></tvar> operator, the <tvar name=2><code>next()</code></tvar> function, and the functions in the <tvar name=3><code>table</code></tvar> library.</translate>
<translate><!--T:115--> If using these is important for your module, you should use your own argument processing function instead of this module.</translate>


<translate>
== See also ==
== Tests == <!--T:116-->
* [[Module:Params]]
</translate>
* {{tl|Template parameter value}}
{{ModuleQuality}}
<includeonly>{{Sandbox other||
<includeonly>{{Sandbox other||
<!-- Categories below this line; interwikis at Wikidata -->
<!-- Categories below this line; interwikis at Wikidata -->
[[Category:Lua metamodules{{#translation:}}]]
[[Category:Wikipedia utility modules]]
}}</includeonly><noinclude>
}}</includeonly>
[[Category:Module documentation pages{{#translation:}}]]
</noinclude>
| #default=
  {{#invoke:Template translation|renderTranslatedTemplate|template=Module:Arguments/doc|noshift=1|uselang={{int:lang}}}}
}}

Revision as of 01:34, 8 June 2024


This module provides easy processing of arguments passed from #invoke. It is a meta-module, meant for use by other modules, and should not be called from #invoke directly (for a module directly invocable by templates you might want to have a look at {{#invoke:params}}). Its features include:

  • Easy trimming of arguments and removal of blank arguments.
  • Arguments can be passed by both the current frame and by the parent frame at the same time. (More details below.)
  • Arguments can be passed in directly from another Lua module or from the debug console.
  • Most features can be customized.

Basic use

First, you need to load the module. It contains one function, named getArgs.

local getArgs = require('Module:Arguments').getArgs

In the most basic scenario, you can use getArgs inside your main function. The variable args is a table containing the arguments from #invoke. (See below for details.)

local getArgs = require('Module:Arguments').getArgs
local p = {}

function p.main(frame)
	local args = getArgs(frame)
	-- Main module code goes here.
end

return p

Recommended practice

However, the recommended practice is to use a function just for processing arguments from #invoke. This means that if someone calls your module from another Lua module you don't have to have a frame object available, which improves performance.

local getArgs = require('Module:Arguments').getArgs
local p = {}

function p.main(frame)
	local args = getArgs(frame)
	return p._main(args)
end

function p._main(args)
	-- Main module code goes here.
end

return p

The way this is called from a template is {{#invoke:Example|main}} (optionally with some parameters like {{#invoke:Example|main|arg1=value1|arg2=value2}}), and the way this is called from a module is require('Module:Example')._main({arg1 = 'value1', arg2 = value2, 'spaced arg3' = 'value3'}). What this second one does is construct a table with the arguments in it, then gives that table to the p._main(args) function, which uses it natively.

Multiple functions

If you want multiple functions to use the arguments, and you also want them to be accessible from #invoke, you can use a wrapper function.

local getArgs = require('Module:Arguments').getArgs

local p = {}

local function makeInvokeFunc(funcName)
	return function (frame)
		local args = getArgs(frame)
		return p[funcName](args)
	end
end

p.func1 = makeInvokeFunc('_func1')

function p._func1(args)
	-- Code for the first function goes here.
end

p.func2 = makeInvokeFunc('_func2')

function p._func2(args)
	-- Code for the second function goes here.
end

return p

Options

The following options are available. They are explained in the sections below.

local args = getArgs(frame, {
	trim = false,
	removeBlanks = false,
	valueFunc = function (key, value)
		-- Code for processing one argument
	end,
	frameOnly = true,
	parentOnly = true,
	parentFirst = true,
	wrappers = {
		'Template:A wrapper template',
		'Template:Another wrapper template'
	},
	readOnly = true,
	noOverwrite = true
})

Trimming and removing blanks

Blank arguments often trip up coders new to converting MediaWiki templates to Lua. In template syntax, blank strings and strings consisting only of whitespace are considered false. However, in Lua, blank strings and strings consisting of whitespace are considered true. This means that if you don't pay attention to such arguments when you write your Lua modules, you might treat something as true that should actually be treated as false. To avoid this, by default this module removes all blank arguments.

Similarly, whitespace can cause problems when dealing with positional arguments. Although whitespace is trimmed for named arguments coming from #invoke, it is preserved for positional arguments. Most of the time this additional whitespace is not desired, so this module trims it off by default.

However, sometimes you want to use blank arguments as input, and sometimes you want to keep additional whitespace. This can be necessary to convert some templates exactly as they were written. If you want to do this, you can set the trim and removeBlanks arguments to false.

local args = getArgs(frame, {
	trim = false,
	removeBlanks = false
})

Custom formatting of arguments

Sometimes you want to remove some blank arguments but not others, or perhaps you might want to put all of the positional arguments in lower case. To do things like this you can use the valueFunc option. The input to this option must be a function that takes two parameters, key and value, and returns a single value. This value is what you will get when you access the field key in the args table.

Example 1: this function preserves whitespace for the first positional argument's value, but trims all other arguments' value and removes all other blank arguments.

local args = getArgs(frame, {
	valueFunc = function (key, value)
		if key == 1 then
			return value
		elseif value then
			value = mw.text.trim(value)
			if value ~= '' then
				return value
			end
		end
		return nil
	end
})

Example 2: this function removes blank arguments and converts all argument values to lower case, but doesn't trim whitespace from positional parameters.

local args = getArgs(frame, {
	valueFunc = function (key, value)
		if not value then
			return nil
		end
		value = mw.ustring.lower(value)
		if mw.ustring.find(value, '%S') then
			return value
		end
		return nil
	end
})

Note: the above functions will fail if passed input that is not of type string or nil. This might be the case if you use the getArgs function in the main function of your module, and that function is called by another Lua module. In this case, you will need to check the type of your input. This is not a problem if you are using a function specially for arguments from #invoke (i.e. you have p.main and p._main functions, or something similar).

Examples 1 and 2 with type checking

Example 1:

local args = getArgs(frame, {
	valueFunc = function (key, value)
		if key == 1 then
			return value
		elseif type(value) == 'string' then
			value = mw.text.trim(value)
			if value ~= '' then
				return value
			else
				return nil
			end
		else
			return value
		end
	end
})

Example 2:

local args = getArgs(frame, {
	valueFunc = function (key, value)
		if type(value) == 'string' then
			value = mw.ustring.lower(value)
			if mw.ustring.find(value, '%S') then
				return value
			else
				return nil
			end
		else
			return value
		end
	end
})

Also, please note that the valueFunc function is called more or less every time an argument is requested from the args table, so if you care about performance you should make sure you aren't doing anything inefficient with your code.

Frames and parent frames

Arguments in the args table can be passed from the current frame or from its parent frame at the same time. To understand what this means, it is easiest to give an example. Let's say that we have a module called Module:ExampleArgs. This module prints the first two positional arguments that it is passed.

Module:ExampleArgs code
local getArgs = require('Module:Arguments').getArgs
local p = {}

function p.main(frame)
	local args = getArgs(frame)
	return p._main(args)
end

function p._main(args)
	local first = args[1] or ''
	local second = args[2] or ''
	return first .. ' ' .. second
end

return p

Module:ExampleArgs is then called by Template:ExampleArgs, which contains the code {{#invoke:ExampleArgs|main|firstInvokeArg}}. This produces the result "firstInvokeArg".

Now if we were to call Template:ExampleArgs, the following would happen:

Code Result
{{ExampleArgs}} firstInvokeArg
{{ExampleArgs|firstTemplateArg}} firstInvokeArg
{{ExampleArgs|firstTemplateArg|secondTemplateArg}} firstInvokeArg secondTemplateArg

There are three options you can set to change this behaviour: frameOnly, parentOnly and parentFirst. If you set frameOnly then only arguments passed from the current frame will be accepted; if you set parentOnly then only arguments passed from the parent frame will be accepted; and if you set parentFirst then arguments will be passed from both the current and parent frames, but the parent frame will have priority over the current frame. Here are the results in terms of Template:ExampleArgs:

frameOnly
Code Result
{{ExampleArgs}} firstInvokeArg
{{ExampleArgs|firstTemplateArg}} firstInvokeArg
{{ExampleArgs|firstTemplateArg|secondTemplateArg}} firstInvokeArg
parentOnly
Code Result
{{ExampleArgs}}
{{ExampleArgs|firstTemplateArg}} firstTemplateArg
{{ExampleArgs|firstTemplateArg|secondTemplateArg}} firstTemplateArg secondTemplateArg
parentFirst
Code Result
{{ExampleArgs}} firstInvokeArg
{{ExampleArgs|firstTemplateArg}} firstTemplateArg
{{ExampleArgs|firstTemplateArg|secondTemplateArg}} firstTemplateArg secondTemplateArg

Notes:

  1. If you set both the frameOnly and parentOnly options, the module won't fetch any arguments at all from #invoke. This is probably not what you want.
  2. In some situations a parent frame may not be available, e.g. if getArgs is passed the parent frame rather than the current frame. In this case, only the frame arguments will be used (unless parentOnly is set, in which case no arguments will be used) and the parentFirst and frameOnly options will have no effect.

Wrappers

The wrappers option is used to specify a limited number of templates as wrapper templates, that is, templates whose only purpose is to call a module. If the module detects that it is being called from a wrapper template, it will only check for arguments in the parent frame; otherwise it will only check for arguments in the frame passed to getArgs. This allows modules to be called by either #invoke or through a wrapper template without the loss of performance associated with having to check both the frame and the parent frame for each argument lookup.

For example, the only content of Template:Side box (excluding content in ‎<noinclude>...‎</noinclude> tags) is {{#invoke:Side box|main}}. There is no point in checking the arguments passed directly to the #invoke statement for this template, as no arguments will ever be specified there. We can avoid checking arguments passed to #invoke by using the parentOnly option, but if we do this then #invoke will not work from other pages either. If this were the case, the |text=Some text in the code {{#invoke:Side box|main|text=Some text}} would be ignored completely, no matter what page it was used from. By using the wrappers option to specify 'Template:Side box' as a wrapper, we can make {{#invoke:Side box|main|text=Some text}} work from most pages, while still not requiring that the module check for arguments on the Template:Side box page itself.

Wrappers can be specified either as a string, or as an array of strings.

local args = getArgs(frame, {
	wrappers = 'Template:Wrapper template'
})


local args = getArgs(frame, {
	wrappers = {
		'Template:Wrapper 1',
		'Template:Wrapper 2',
		-- Any number of wrapper templates can be added here.
	}
})

Notes:

  1. The module will automatically detect if it is being called from a wrapper template's /sandbox subpage, so there is no need to specify sandbox pages explicitly.
  2. The wrappers option effectively changes the default of the frameOnly and parentOnly options. If, for example, parentOnly were explicitly set to 0 with wrappers set, calls via wrapper templates would result in both frame and parent arguments being loaded, though calls not via wrapper templates would result in only frame arguments being loaded.
  3. If the wrappers option is set and no parent frame is available, the module will always get the arguments from the frame passed to getArgs.

Writing to the args table

Sometimes it can be useful to write new values to the args table. This is possible with the default settings of this module. (However, bear in mind that it is usually better coding style to create a new table with your new values and copy arguments from the args table as needed.)

args.foo = 'some value'

It is possible to alter this behaviour with the readOnly and noOverwrite options. If readOnly is set then it is not possible to write any values to the args table at all. If noOverwrite is set, then it is possible to add new values to the table, but it is not possible to add a value if it would overwrite any arguments that are passed from #invoke.

Ref tags

This module uses metatables to fetch arguments from #invoke. This allows access to both the frame arguments and the parent frame arguments without using the pairs() function. This can help if your module might be passed ‎<ref>...‎</ref> tags as input.

As soon as ‎<ref>...‎</ref> tags are accessed from Lua, they are processed by the MediaWiki software and the reference will appear in the reference list at the bottom of the article. If your module proceeds to omit the reference tag from the output, you will end up with a phantom reference – a reference that appears in the reference list but without any number linking to it. This has been a problem with modules that use pairs() to detect whether to use the arguments from the frame or the parent frame, as those modules automatically process every available argument.

This module solves this problem by allowing access to both frame and parent frame arguments, while still only fetching those arguments when it is necessary. The problem will still occur if you use pairs(args) elsewhere in your module, however.

Known limitations

The use of metatables also has its downsides. Most of the normal Lua table tools won't work properly on the args table, including the # operator, the next() function, and the functions in the table library. If using these is important for your module, you should use your own argument processing function instead of this module.

See also