crown-engine/samples/core/lua/class.lua

function class(klass, super)
	if not klass then
		klass = {}

		local meta = {}
		meta.__call = function(self, ...)
			local object = {}
			setmetatable(object, klass)
			if object.init then object:init(...) end
			return object
		end
		setmetatable(klass, meta)
	end

	if super then
		for k,v in pairs(super) do
			klass[k] = v
		end
	end
	klass.__index = klass

	return klass
end