Module:Labelled list hatnote/doc

This is a documentation subpage for Module:Labelled list hatnote.
It may contain usage information, categories and other content that is not part of the original module page.

This Lua module is used in MediaWiki:Wantedpages-summary, and on approximately 580,000 pages, or roughly 1% of all pages.
Changes to it can cause immediate changes to the Wikipedia user interface.
To avoid major disruption and server load, any changes should be tested in the module's /sandbox or /testcases subpages, or in your own module sandbox. The tested changes can be added to this page in a single edit. Please discuss changes on the talk page before implementing them.

This module depends on the following other modules:

This module provides a handful of functions that make it easy to implement hatnotes that take the form of a label in front of a list of pages, e.g.

Usage

labelledList

Invoking the labelledList() function is enough to implement most such templates:

{{#invoke:Labelled list hatnote|labelledList|Universal label}}

or

{{#invoke:Labelled list hatnote|labelledList|Singular label|Plural label}}

For example, providing "See also" instead of "Universal label" duplicates the functionality of {{see also}}, while providing "Main article" and "Main articles" instead of "Singular label" and "Plural label" duplicates the (article namespace) functionality of {{main}}.

If third and fourth labels are provided, they'll be used in the case where any of the target pages are outside the article namespace, so e.g. {{main}} can be implemented thus:

{{#invoke:Labelled list hatnote|labelledList|Main article|Main articles|Main page|Main pages}}

preprocessDisplays

The preprocessDisplays() function takes a raw list of arguments and combines in any display arguments. For example, {{see also|1|l1=One}} initially has the arguments table {'1', ['l1'] = 'One'}; this table would combine those into the table {'1|One'}. It overrides manual piping (e.g. {{see also|1{{!}}2|l1=One}} → {'1|One'}) and compresses sparse arrays if a parameter is skipped or left empty.

Example:

local mLabelledList = require('Module:Labelled list hatnote')
local pages = mLabelledList.preprocessDisplays(args)

_labelledList

For modules that need to modify the functionality slightly while still using it, _labelledList() provides some flexibility. It takes three parameters:

A pages list, preferably preprocessed and compressed by preprocessDisplays
A labels table, where the first item is the singular or universal label, and the second either a plural label or a copy of the first.
An options table, preferably containing:
- a template string with the full title of the template. Defaults to the title of this module.
- a category string (or nil) as taken by makeWikitextError from Module:Hatnote, to optionally disable error categories
- a selfref string (or nil) as taken by _hatnote to enable the selfref option

Example:

local mLabelledList = require('Module:Labelled list hatnote')
return mLabelledList._labelledList(pages, labels, options)

Errors

This module causes templates based on it to produce an error message if no page names are provided as template parameters. Normally, these should lead back to "Errors" sections in the documentation of those templates. However, if those templates use a module with _labelledList() and don't provide a template item in their options table, that error defaults to leading back here. The error can be solved by providing at least one valid page-name parameter to the template in question; the problem in the template can be fixed by providing some value to the template item of the _labelledList() options table.