Guidelines:Modules

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Overview

Modules are Lua scripts for making templates using a full-fledged programming language. You can ask questions about Zelda Wiki modules in the #modules [Discord Discord] channel.

Getting Started

In order to contribute to modules, you'll need to learn basic programming in Lua. You'll also need to know the specifics of Lua scripting on MediaWiki.

Lua

Developers

If you already have some programming experience in other languages, note the following particularities of Lua.

Particularities	Further reading
tables are the only built-in object type. Any use of the term "array" actually refers to a table with integer keys. The language offers prototype-based inheritance through metatables.	Tables Metatables and Metamethods
Generally tables are 1-indexed as opposed to 0-indexed. local tbl = {"foo"} tbl[1] > "foo"	Arrays
The ipairs iterator is for integer key-value pairs in a table. The pairs iterator is for all key-value pairs, integer or otherwise.	Generic for Numeric for
The length operator for a table is #. # replaces the table.getn seen in the online version of Programming in Lua, which is for Lua 5.0. getn won't work here as the wiki is on Lua 5.1 (at the time of writing). table.setn was also deprecated and is unusable in 5.1. Unfortunately, the alternative __len field is only available in Lua 5.2.
Tables, nil, and the # operator don't interact the way similar constructs do in other languages. #{ nil, nil, "foo" } > 3 local tbl = {} tbl[3] = "foo" #tbl > 0 tbl[1] = "bar" #tbl > 1 tbl[2] = "baz" #tbl > 3

Scribunto

For a broader, more in-depth guide, see Gamepedia Help Wiki.

See also the full Scribunto/Lua reference manual.

Scribunto is the name of the extension that enables modules. It is the term used for concepts that are Lua-related but specific to MediaWiki.

The Lua on you see on MediaWiki is almost the same as standard Lua except for some changes to library functions and packages. The main difference is in how Lua scripts are invoked.

#invoke

The #invoke parser function is what bridges the gap between templates and module scripts. For example, the transcluded content of Template:Figurine is as follows:

{{#invoke:Figurine|Main}}

This invokes Module:Figurine, which looks be something like:

local p = {}
local h = {}
local utilsGame = require("Module:UtilsGame")
...

function p.Main(frame)
    local args = frame:getParent().args
    local result = h.getFigurine(args[1], args[2])
    return result
end

function h.getFigurine(game, name)
...
end

return p

A page can invoke any function that is a field on the module's export table. The export table is the table object returned by the module, which is always named p by convention. In this case, Main is the only function in the export table.

args

Functions called via #invoke are passed a Frame object. frame.args is a table of the arguments to #invoke—there are none in the above example. However, frame:getParent().args represents the template arguments. For example, if a page has {{Figurine|TMC|Minish Ezlo}}, then frame:getParent().args[1] evaluates to the string TMC in that invocation.

The # operator and most other table functions don't work on frame.args.

require

A module can import another module and use its exported functions. This is done with the require function, as shown in the above example with Module:UtilsGame.

mw

Scribunto adds several libraries that are pre-loaded on all modules as the mw object. The following libraries are of note, in addition to the base functions:

Library	Usage example
mw.text	Module:List
mw.title	Module:Subpage List
mw.html	Module:Infobox2

Testing and Debugging

You should never be in a situation where you're blindly submitting code and hoping that it works. In the Preview page with this form just below the "Save changes" button, input a page name in the Page title field and click "Show preview" next to it. This will show you how that page will look with your changes to the module. A good page to preview is the module documentation page when it has use cases (as Module:UtilsMarkup/doc does, for example), or the corresponding template documentation when it has usage examples (e.g. Template:Term/Documentation). Consequently, creating documentation examples ahead of time and previewing them can be an effective way to develop modules.

Utility Modules

A utility module is a library-type module meant to be used by other modules, rather than being invoked by a template. Most template-facing modules use at least one of these:

• Module:UtilsGame
• Module:UtilsMarkup
• Module:UtilsTable

A complete list of utility modules can be found here.

Leverage utility modules as much as possible so that the wiki's modules stay DRY.

Higher-Order Functions

In utility modules such as Module:UtilsTable, you'll often see functions like these:

utilsTable.isEqual({})({})
> true

You might've expected the usual function syntax utilsTable.isEqual({}, {}) instead. The above is an example of a higher-order function—a function that returns a function. The function call above is shorthand for:

local isEmpty = utilsTable.isEqual({})
isEmpty({})
> true

Functions are written this way for increased reusability. They are often composed with the other type of higher-order function—one that accepts a function as an argument:

local isEmpty = utilsTable.isEqual({})
local notEmpty = utilsFunction.negate(isEmpty)
local magicWords = utilsTable.filter(notEmpty)({ {}, {}, {"Kooloo"}, {"Limpah"} })
utilsTable.flatten(magicWords)
> { "Kooloo", "Limpah" }

Notes

Guidelines

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Main

Account Migration • Code of Conduct • Getting Started • Main Guidelines

Content

Articles • Boilerplates • Cameos • Canon • Categories • Files • New Games • Redirects • References • Sandboxes • Terminology • Theories • Translations

Games and Books

Breath of the Wild • Encyclopedia • Hyrule Warriors: Age of Calamity • Link's Awakening for Nintendo Switch • Tears of the Kingdom

Technical

Animated PNGs • Bots • Cargo • CSS • Modules^{(Data, Exercises)} • Moving Pages • Pywikibot

Templates

{{Categories}} • {{Media}} • {{Navbox}} • {{Term}}

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