Editing Module:Category handler/doc (section)

=== Advanced usage ===

This module takes one or more parameters named after the different page types as listed in section [[#Namespaces|namespaces]] above. By using those parameters you can specify exactly in which namespaces your template should categorize. Like this:

<syntaxhighlight lang="lua">
p = {}
local categoryHandler = require( 'Module:Category handler' ).main
 
function p.main( frame )
    local result = 'This is a module meant for articles and talk pages.'
    local category = categoryHandler{
        main = '[[Category:Somecat1]]', -- Categorize in main (article) space
        talk = '[[Category:Somecat2]]', -- Categorize in talk space
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end
 
return p
</syntaxhighlight>

The above module will only categorize in main and talk space. But it will not categorize on /archive pages since they are blacklisted. (See section [[#Blacklist|blacklist]] below.) And if you need to demonstrate (discuss) the module on a talkpage, then you can feed "<code>nocat='true'</code>" to prevent that template from categorizing. (See section [[#Nocat|nocat]] below.) Like this:

<pre>
== My new module ==
Hey guys, have you seen my new module?
{{#invoke:mymodule|main|nocat=true}}
Nice, isn't it?
--~~~~
</pre>

Sometimes we want to use the same category in several namespaces, then do like this:

<syntaxhighlight lang="lua">
p = {}
local categoryHandler = require( 'Module:Category handler' ).main
 
function p.main( frame )
    local result = 'This is a module used in several namespaces.'
    local category = categoryHandler{
        main = '[[Category:Somecat1]]',
        [ 1 ] = '[[Category:Somecat2]]', -- For help and user space
        help = 1,
        user = 1,
        talk = '', -- No categories on talk pages
        other = '[[Category:Somecat3]]', -- For all other namespaces
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end
 
return p
</syntaxhighlight>

In the above example we use a numbered parameter to feed one of the categories, and then we tell this module to use that numbered parameter for both the help and user space.

The category handler module understands an unlimited number of numbered parameters.

The '''other''' parameter defines what should be used in the remaining namespaces that have not explicitly been fed data.

Note the empty but defined '''talk''' parameter. That stops this module from showing what has been fed to the '''other''' parameter, when in talk space.

The category handler module also has a parameter called '''all'''. It works like this:

<syntaxhighlight lang="lua">
p = {}
local categoryHandler = require( 'Module:Category handler' ).main
 
function p.main( frame )
    local result = 'This is a module used in all namespaces.'
    local category = categoryHandler{
        all = '[[Category:Somecat1]]', -- Categorize in all namespaces
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end
 
return p
</syntaxhighlight>

The above example will categorize in all namespaces, but not on blacklisted pages. If you want to demonstrate that module on a page, then use "<code>nocat=true</code>" to prevent the template from categorizing. 

We suggest avoiding the '''all''' parameter, since modules and templates should preferably only categorize in the namespaces they need to.

The all parameter can also be combined with the rest of the parameters. Like this:

<syntaxhighlight lang="lua">
p = {}
local categoryHandler = require( 'Module:Category handler' ).main
 
function p.main( frame )
    local result = 'This is a module used in all namespaces.'
    local category = categoryHandler{
        all = '[[Category:Somecat1]]', -- Categorize in all namespaces
        main = '[[Category:Somecat2]]', -- And add this in main space
        other = '[[Category:Somecat3]]', -- And add this in all other namespaces
        nocat = frame.args.nocat -- So "nocat=true/false" works
    }
    category = category or '' -- Check that we don't have a nil value for the category variable.
    return result .. category
end
 
return p
</syntaxhighlight>

If the above module is placed on an article, then it will add the categories "Somecat1" and "Somecat2". But on all other types of pages it will instead add "Somecat1" and "Somecat3". As the example shows, the all parameter works independently of the rest of the parameters.