Lua/Tutorial/fr

Bienvenu sur le tutoriel Scribunto-Lua destiné à aider les débutants à apprendre Lua pour écrire des script pour MediaWiki. Vous pouvez aussi lire le tutoriel présenté au Hackathon 2012 à Berlin (en anglais).

Ce tutoriel a été développé à l’origine pour le Hackathon 2012 à Berlin, comme événement en face-à-face. Il a été adapté pour le wiki, à distance, tel que vous le voyez ici. Comme tout être wiki, c’est un document vivant et nous vous encourageons à participer en anglais ou en français pour le développer et le maintenir.

Le contenu ci-dessous se focalise sur l’apprentissage pour des développeurs de modèles MediaWiki. Tout le monde est invité à l’utiliser. Si vous êtes nouveau dans l’écriture de modèles MediaWiki mais que vous avez de l’expérience en Lua, vous pouvez vous renseigner plus sur les modèles. Notez que quelques détails dans Scribunto ne s’appliquent pas à la distribution Lua. Si vous êtes un gourou des modèles MediaWiki, mais nouveau en Lua, vous apprendrez une nouvelle magie sympa. Si vous êtes nouveau dans les deux, vous verrez que la communauté MediaWiki a plusieurs personnes qui peuvent vous aider à apprendre.

• Lua scripting general information and brief historical context of its planned use in MediaWiki.
  • Status of Lua scripting on MediaWiki
  • What is Lua? Check out the Lua.org demo if you don't want to download Scribunto just yet.
  • Lua evolution PDF and version history
• What is different from JS and OO languages we could have used?
  • Scribunto: How is the Lua implementation in MediaWiki different?

WikiText does not parse the way you would normally expect. Parser frames are arguments in Scribunto templates. Strip markers replace certain markup, which if it is passed, will result in placeholders instead of markup. You will need to use the new Namespace:Module

• How you adapt for these differences

Please post the link to a template that you'd like to see adapted to Lua as a demo, on-stage during the tutorial.

1. (first template suggestion)

• Create a page in the Module namespace
• Write some Lua code in it. Here is the boilerplate:

local p = {}
function p.hello(frame)
    return 'Hello'
end
return p

• Go to the module talk page
• Put a #invoke in it to invoke your new module

{{#invoke: my_module | hello }}

Functions can access the frame object to get access to the parameters that the template was invoked with. For example, let's change the previous module so that it takes two arguments, like this:

{{#invoke: my_module | hello | hair | brown }}

Our Lua function can use the parameters "hair" and "brown" in either of two ways:

1. Access them directly as frame.args[1] and frame.args[2], respectively (named arguments can also be used, such as frame.args["title"] or frame.args.title)
2. Iterate them using the frame:argumentPairs() function, which returns a (name, value) pair for each; this is the best way to code a template that can take a variable number of parameters

Here's a simple example of a function that uses the parameters:

local p = {}
function p.hello(frame)
    return 'Hello, my ' .. frame.args[1] .. ' is ' .. frame.args[2]
end
return p

A few pitfalls to avoid:

1. The parameter values are always strings, even if they are numeric in form; you can use the Lua function tonumber() if you need to treat a value as a number.
2. However, numbered parameter keys are numbers, even if they are given explicitly in the template invocation (for example, the parameters in both {{#invoke:my_module | hello | world}} and {{#invoke:my_module | hello | 1=world}} are indexed by the number 1, not the string "1"
3. With explicitly named (or numbered) parameters, leading and trailing whitespace is stripped from name and value. This is similar to template parameters.
4. An empty string value is not the same as a missing value, which is nil; for example,

   {{#invoke:my_module | hello | world }}

   results in frame.args[2] being nil (which will cause a script error in the example code above), but

   {{#invoke:my_module | hello | world | }}

   results in frame.args[2] being an empty string (which will not, although the resulting text will look odd). One way to work around this is to assign the desired parameters to a local variable, and replacing nils with empty strings at this step; e.g.,

    local arg2 = frame.args[2] or ""

• Return value expansion, access to the frame object and bug fixing

• Lua 5.1 Reference Manual
• Programming in Lua

If you saw this tutorial live, in Berlin, please give us your feedback on the Talk page, so we can refine it for future hackathons and other events. You can give anonymous feedback if you prefer.

Tutorial slide deck from Berlin