classic.lua with getters & setters

classic.lua

--
-- classic
--
-- Copyright (c) 2014, rxi
--
-- This module is free software; you can redistribute it and/or modify it under
-- the terms of the MIT license. See LICENSE for details.
--


local Object = {}
Object.__index = Object


function Object:new()
end


local function __index(self, k)
	local cls = getmetatable(self)
	local get = rawget(cls, 'get_'..k)
	if get then
		return get(self, k)
	else
		local super = rawget(cls, 'super')
		if super then
			return super[k]
		end
	end
end

local function __newindex(self, k, v)
	local cls = getmetatable(self)
	local set = rawget(cls, 'set_'..k)
	if set then
		set(self, k, v)
	else
		rawset(self, k, v)
	end
end

function Object:extend()
  local cls = {}
  for k, v in pairs(self) do
    if k:find("__") == 1 then
      cls[k] = v
    end
  end
  cls.__index = __index
  cls.__newindex = __newindex
  cls.super = self
  setmetatable(cls, self)
  return cls
end


function Object:implement(...)
  for _, cls in pairs({...}) do
    for k, v in pairs(cls) do
      if self[k] == nil and type(v) == "function" then
        self[k] = v
      end
    end
  end
end


function Object:is(T)
  local mt = getmetatable(self)
  while mt do
    if mt == T then
      return true
    end
    mt = getmetatable(mt)
  end
  return false
end


function Object:__call(...)
  local obj = setmetatable({}, self)
  obj:new(...)
  return obj
end


if not ... then --demo

	Foo = Object:extend()

	local private_x
	function Foo:get_x()
		print('getting x', private_x)
		return private_x
	end

	function Foo:set_x(x)
		print('setting x to', x)
		private_x = x
	end

	local foo = Foo()

	foo.x = 5
	print(foo.x)

end


return Object