LuaWML/Files

This page describes the LuaWML functions for handling Lua files.

wesnoth.dofile

Replaces basic.dofile for loading files. Loads the given filename (relative to the content directory) and executes it in an unprotected environment (that is, exceptions propagate to the caller). Returns the values returned by the executed script.

wesnoth.dofile "~add-ons/MyCampaign/lua/scenario-utils.lua"

It may be helpful to put as many Lua code as possible in specific files instead of embedding it into WML files, so as to not confuse text editors. Then a scenario only needs to contain the following event:

[event]
    name = preload
    first_time_only = no
    [lua]
        code = << wesnoth.dofile "~add-ons/MyCampaign/lua/scenario-utils.lua" >>
    [/lua]
[/event]

If the same files need to be loaded for all the scenarios, the [lua] tag above can be directly put inside the _main.cfg file (or equivalent file). The Lua code will then be executed at the start of each scenario.

(Version 1.13.8 and later only) If you pass additional arguments to dofile, they are forwarded to the script in the "..." variable.

wesnoth.require

Loads the given filename (relative to the content directory) and executes it in a protected environment. If the file has already been executed once, then compilation and execution are skipped and the value from its previous run is returned.

helper = wesnoth.require "lua/helper.lua"

This function is helpful in writing libraries of functions that can be accessed from various places. So the return value of the file is supposed to be a table containing the methods provided by the library. Such a library would look like:

local library = {}
function library.do_something(a) ... end
function library.go_somewhere(x, y) ... end
return library

It can also be helpful when writing unit types with events, since unit types are not necessarily available at preload time, hence preventing the usage of #wesnoth.dofile for precompiling code:

[unit_type]
    id = phoenix
    [event]
        name = last breath
        [lua]
            code = << wesnoth.require("~add-ons/MyEra/lua/unit-utils.lua").resurrect(...) >>
        [/lua]
    [/event]
[/unit_type]

(Version 1.13.8 and later only)The ".lua" file extension is now added for you automatically, as is the "lua/" prefix. Both these substitutions only occur if the file without the substitutions does not exist. Taken together, this means that you can now write:

wesnoth.require "helper"
wesnoth.require "~add-ons/MyEra/lua/unit-utils"

wesnoth.have_file

(Version 1.13.7 and later only)

Tests if a file exists. Files are resolved in the same way as by dofile. (Version 1.13.8 and later only) If you pass true as the second argument, it returns true only if the file is a regular file — otherwise, it returns true if the path is valid, whether it is a file, directory, or some other type of object.

wesnoth.read_file

(Version 1.13.7 and later only)

Reads a file into a string. (Version 1.13.8 and later only) If the path is a directory, this instead returns an array of the directory contents, with directories first, followed by files. The special key ndirs contains the number of directories.