From b5fcac7ed53d14bf3bbf8e6ef9795ef4de0ed6db Mon Sep 17 00:00:00 2001 From: rubenwardy Date: Sun, 31 Jul 2022 17:39:25 +0100 Subject: [PATCH] Lua Scripting: Update chapter --- _en/basics/lua.md | 64 +++++++++++++++++++++++++---------------------- 1 file changed, 34 insertions(+), 30 deletions(-) diff --git a/_en/basics/lua.md b/_en/basics/lua.md index 52bc164..71f17c4 100644 --- a/_en/basics/lua.md +++ b/_en/basics/lua.md @@ -9,8 +9,8 @@ redirect_from: /en/chapters/lua.html ## Introduction -In this chapter we'll talk about scripting in Lua, the tools required -to assist with this, and some techniques which you may find useful. +In this chapter, you'll learn about scripting in Lua, the tools required +to help with this, and some techniques that you may find useful. - [Programming](#programming) - [Coding in Lua](#coding-in-lua) @@ -24,23 +24,21 @@ to assist with this, and some techniques which you may find useful. Programming is the action of taking a problem, such as sorting a list of items, and turning it into steps that a computer can understand. - Teaching you the logical process of programming is beyond the scope of this book; however, the following websites are quite useful in developing this: * [Codecademy](http://www.codecademy.com/) is one of the best resources for learning to write code. It provides an interactive tutorial experience. * [Scratch](https://scratch.mit.edu) is a good resource for starting from - absolute basics, and learning the problem-solving techniques required to program.\\ - Scratch is *designed to teach children* how to program and isn't a serious - programming language. + absolute basics, and learning the problem-solving techniques required to program. + It's great for children and teenagers. * [Programming with Mosh](https://www.youtube.com/user/programmingwithmosh) is a good YouTube series to learn programming. ### Coding in Lua It's also beyond the scope of this book to teach Lua coding. -The [Programming in Lua](https://www.lua.org/pil/contents.html) book is an +The [Programming in Lua (PiL)](https://www.lua.org/pil/contents.html) book is an excellent introduction to Lua programming. @@ -74,10 +72,10 @@ Functions which come with Lua by default, such as `table.insert`, are also highl Commonly used editors which are well-suited for Lua include: -* [VSCode](https://code.visualstudio.com/) - +* [VSCode](https://code.visualstudio.com/): open source (as Code-OSS or VSCodium), popular, and has - [plugins for Minetest modding](https://marketplace.visualstudio.com/items?itemName=GreenXenith.minetest-tools). -* [Notepad++](http://notepad-plus-plus.org/) - Windows-only + [plugins for Minetest](https://marketplace.visualstudio.com/items?itemName=GreenXenith.minetest-tools). +* [Notepad++](http://notepad-plus-plus.org/): simple, Windows-only Other suitable editors are also available. @@ -85,8 +83,25 @@ Other suitable editors are also available. ## Local and Global Scope Whether a variable is local or global determines where it can be written to or -read from. A local variable is only accessible from where it is defined. Here -are some examples: +read from. Global variables can be accessed from anywhere in the script file, +and from any other mod: + +```lua +function one() + foo = "bar" +end + +function two() + print(dump(foo)) -- Output: "bar" +end + +one() +two() +``` + +In constrast, a local variable is only accessible from where it is defined. +Lua defaults to variables being global, so you need to explicitly use the +`local` keyword: ```lua -- Accessible from within this script file @@ -103,22 +118,6 @@ function myfunc() end ``` -In contrast, global variables can be accessed from anywhere in the script file, and -from any other mod. - -```lua -function one() - foo = "bar" -end - -function two() - print(dump(foo)) -- Output: "bar" -end - -one() -two() -``` - ### Locals should be used as much as possible @@ -170,6 +169,9 @@ end mymod.foo("foobar") ``` +`function mymod.foo()` is equivalent to `mymod.foo = function()`, it's just a +nicer way to write it. + ## Including other Lua Scripts The recommended way to include other Lua scripts in a mod is to use *dofile*. @@ -182,11 +184,13 @@ A script can return a value, which is useful for sharing private locals: ```lua -- script.lua -return "Hello world!" +local module = {} +module.message = "Hello World!" +return module -- init.lua local ret = dofile(minetest.get_modpath("modname") .. "/script.lua") -print(ret) -- Hello world! +print(ret.message) -- Hello world! ``` [Later chapters](../quality/clean_arch.html) will discuss how best to split up