class.lua

Class = {}

-- default (empty) constructor
function Class:init(...) end

-- create a subclass
function Class:extend(obj, is_new)
	local obj = obj or {}

	local function copyTable(table, destination)
		local table = table or {}
		local result = destination or {}

		for k, v in pairs(table) do
			if not result[k] then
				if type(v) == "table" and k ~= "__index" and k ~= "__newindex" then
					result[k] = copyTable(v)
				else
					result[k] = v
				end
			end
		end

		return result
	end

	copyTable(self, obj)

	obj._ = obj._ or {}

	if not is_new then
		obj.super = self
	end

	-- create new objects directly, like o = Object()
	obj.__call = function(self, ...)
		return self:new(...)
	end

	setmetatable(obj, obj)

	return obj
end

-- set properties outside the constructor or other functions
function Class:set(prop, value)
	if not value and type(prop) == "table" then
		for k, v in pairs(prop) do
			rawset(self._, k, v)
		end
	else
		rawset(self._, prop, value)
	end
end

-- create an instance of an object with constructor parameters
function Class:new(...)
	local obj = self:extend({}, true)
	if obj.init then obj:init(...) end
	return obj
end


function class(attr)
	attr = attr or {}
	return Class:extend(attr)
end