Load Lua-files by relative path

lua require coronasdk
RocketR picture RocketR · Feb 5, 2012 · Viewed 61.6k times · Source

If I have a file structure like this:

./main.lua
./mylib/mylib.lua
./mylib/mylib-utils.lua
./mylib/mylib-helpers.lua
./mylib/mylib-other-stuff.lua

From main.lua the file mylib.lua can be loaded with full path require('mylib.mylib'). But inside mylib.lua I would also like to load other necessary modules and I don't feel like always specifying the full path (e.g. mylib.mylib-utils). If I ever decide to move the folder I'm going to have a lot of search and replace. Is there a way to use just the relative part of the path?

UPD. I'm using Lua with Corona SDK, if that matters.

Answer

kikito picture kikito · Feb 5, 2012

There is a way of deducing the "local path" of a file (more concretely, the string that was used to load the file).

If you are requiring a file inside lib.foo.bar, you might be doing something like this:

require 'lib.foo.bar'

Then you can get the path to the file as the first element (and only) ... variable, when you are outside all functions. In other words:

-- lib/foo/bar.lua
local pathOfThisFile = ... -- pathOfThisFile is now 'lib.foo.bar'

Now, to get the "folder" you need to remove the filename. Simplest way is using match:

local folderOfThisFile = (...):match("(.-)[^%.]+$") -- returns 'lib.foo.'

And there you have it. Now you can prepend that string to other file names and use that to require:

require(folderOfThisFile .. 'baz')     -- require('lib.foo.baz')
require(folderOfThisFile .. 'bazinga') -- require('lib.foo.bazinga')

If you move bar.lua around, folderOfThisFile will get automatically updated.

Related questions

How to create include files in Lua language?

I want to create a header file in Lua (header.lua), then execute the require function to load it. How do I execute require to a file that I have created?

Read More
In Lua how do you import modules?

Do you use require "name" or local name = require "name" Also, do you explicitly declare system modules as local variables? E.g. local io = require "io" Please explain your choice. Programming in Lua 2ed says "if she prefers to use …

Read More
Split string in Lua?

I need to do a simple split of a string, but there doesn't seem to be a function for this, and the manual way I tested didn't seem to work. How would I do it?

Read More