>@3: -- $Id: LibStub.lua 76 2007-09-03 01:50:17Z mikk $
>@3: -- LibStub is a simple versioning stub meant for use in Libraries.  http://www.wowace.com/wiki/LibStub for more info
>@3: -- LibStub is hereby placed in the Public Domain
>@3: -- Credits: Kaelten, Cladhaire, ckknight, Mikk, Ammo, Nevcairiel, joshborke
>@3: local LIBSTUB_MAJOR, LIBSTUB_MINOR = "LibStub", 2  -- NEVER MAKE THIS AN SVN REVISION! IT NEEDS TO BE USABLE IN ALL REPOS!
>@3: local LibStub = _G[LIBSTUB_MAJOR]
>@3: 
>@3: -- Check to see is this version of the stub is obsolete
>@3: if not LibStub or LibStub.minor < LIBSTUB_MINOR then
>@3: 	LibStub = LibStub or {libs = {}, minors = {} }
>@3: 	_G[LIBSTUB_MAJOR] = LibStub
>@3: 	LibStub.minor = LIBSTUB_MINOR
>@3: 	
>@3: 	-- LibStub:NewLibrary(major, minor)
>@3: 	-- major (string) - the major version of the library
>@3: 	-- minor (string or number ) - the minor version of the library
>@3: 	-- 
>@3: 	-- returns nil if a newer or same version of the lib is already present
>@3: 	-- returns empty library object or old library object if upgrade is needed
>@3: 	function LibStub:NewLibrary(major, minor)
>@3: 		assert(type(major) == "string", "Bad argument #2 to `NewLibrary' (string expected)")
>@3: 		minor = assert(tonumber(strmatch(minor, "%d+")), "Minor version must either be a number or contain a number.")
>@3: 		
>@3: 		local oldminor = self.minors[major]
>@3: 		if oldminor and oldminor >= minor then return nil end
>@3: 		self.minors[major], self.libs[major] = minor, self.libs[major] or {}
>@3: 		return self.libs[major], oldminor
>@3: 	end
>@3: 	
>@3: 	-- LibStub:GetLibrary(major, [silent])
>@3: 	-- major (string) - the major version of the library
>@3: 	-- silent (boolean) - if true, library is optional, silently return nil if its not found
>@3: 	--
>@3: 	-- throws an error if the library can not be found (except silent is set)
>@3: 	-- returns the library object if found
>@3: 	function LibStub:GetLibrary(major, silent)
>@3: 		if not self.libs[major] and not silent then
>@3: 			error(("Cannot find a library instance of %q."):format(tostring(major)), 2)
>@3: 		end
>@3: 		return self.libs[major], self.minors[major]
>@3: 	end
>@3: 	
>@3: 	-- LibStub:IterateLibraries()
>@3: 	-- 
>@3: 	-- Returns an iterator for the currently registered libraries
>@3: 	function LibStub:IterateLibraries() 
>@3: 		return pairs(self.libs) 
>@3: 	end
>@3: 	
>@3: 	setmetatable(LibStub, { __call = LibStub.GetLibrary })
>@3: end