Add standard Lua Class implementation

maps/includes/base.lua

@@ -6,8 +6,8 @@
 -- This file is loaded automatically whenever a map is loaded.
 -- Do not change this file.
 -----------------------------------------------------------------------------
-local _G = getfenv(0)
 
+Class = require "util.class"
 
 -----------------------------------------------------------------------------
 -- defines

maps/includes/util/class.lua

@@ -0,0 +1,46 @@
+-- from http://lua-users.org/wiki/SimpleLuaClasses
+
+function Class(base, _ctor)
+	local c = {}    -- a new class instance
+	if not _ctor and type(base) == 'function' then
+		_ctor = base
+		base = nil
+	elseif type(base) == 'table' then
+		-- our new class is a shallow copy of the base class!
+		for i,v in pairs(base) do
+			c[i] = v
+		end
+		c._base = base
+	end
+
+	-- the class will be the metatable for all its objects,
+	-- and they will look up their methods in it.
+	c.__index = c
+
+	-- expose a constructor which can be called by <classname>(<args>)
+	local mt = {}
+
+	mt.__call = function(class_tbl, ...)
+		local obj = {}
+		setmetatable(obj,c)
+
+		if c._ctor then
+			c._ctor(obj,...)
+		end
+		return obj
+	end
+
+	c._ctor = _ctor
+	c.is_a = function(self, klass)
+		local m = getmetatable(self)
+		while m do 
+			if m == klass then return true end
+			m = m._base
+		end
+		return false
+	end
+	setmetatable(c, mt)
+	return c
+end
+
+return Class