require

val = require (modname)

Loads the named module.

First checks the table package.loaded to see if it has already been loaded. If so, returns the value there.

Otherwise it tries to find a loader for the module. It tries these things:

• If the table item package.preload [modname] is a function, that is called as the module loader.
• Process the variable package.path, substituting modname where it has a "?" (that is, ? becomes the name) and then repeatedly attempting to open the files in the list (paths separated by semicolons) as Lua source files. The first attempt in the default configuration is in the current directory, for modname.lua, then in the executable directory (that is, where MUSHclient executable is, if you are running from MUSHclient), various combinations of subdirectories and file names. To see exactly what tests are being done, just type 'require "foo"' and the error message will show you.
• Process the variable package.cpath, substituting modname where it has a "?" (that is, ? becomes the name) and then repeatedly attempting to open the files in the list (paths separated by semicolons) as DLLs. This attempts to load various DLLs, again see the package.cpath variable to see which ones exactly, or try a dummy require, as described above. If a DLL is found it attempts to call the function "luaopen_" concatenated with the module name, where dots are replaced by underscores.
• Finally if all else fails try to load the all-in-one loader (executable-path/loadall.dll) and look for an appropriate function.

Once a loader is found, require calls the loader with a single argument, modname. If the loader returns any value, require assigns the returned value to package.loaded [modname]. If the loader returns no value and has not assigned any value to package.loaded [modname], then require assigns true to this entry. In any case, require returns the final value of package.loaded [modname].

f = require ("test")  --> loads module "test" 

Effectively this lets various modules "require" a package, and it will only be loaded once. Also see the description for "module" for ways of effectively setting up a module to work in conjunction with "require".