Hmm, I'm now using a much simpler implementation of classes derived from (but not equivalent to) bartbes'. LoveObject is overly-complicated in comparison... That said, this version doesn't support multiple inheritance.
Code: Select all
----------------------------------------------------------------------------
-- Copyright (c) 2009 Bart Bes
--
-- Permission is hereby granted, free of charge, to any person
-- obtaining a copy of this software and associated documentation
-- files (the "Software"), to deal in the Software without
-- restriction, including without limitation the rights to use,
-- copy, modify, merge, publish, distribute, sublicense, and/or sell
-- copies of the Software, and to permit persons to whom the
-- Software is furnished to do so, subject to the following
-- conditions:
--
-- The above copyright notice and this permission notice shall be
-- included in all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
-- EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
-- OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
-- NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
-- HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
-- WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
-- FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
-- OTHER DEALINGS IN THE SOFTWARE.
----------------------------------------------------------------------------
-- Single Inheritance Classes.
local class, class_mt={}, {}
class.__index=class
setmetatable(class, class_mt)
function class_mt:__index(key)
if rawget(self, "__class") then
return self.__class[key]
end
return nil
end
function class:new(...)
-- Call this to make an instance from a class. ... are init parameters
local c = {}
c.__class = self
c.__index=c
setmetatable(c, self)
if self.init then
c=self.init(c, ...)
end
return c
end
function class:subclass(t)
-- Call this to subclass the class. t is a table.
-- i.e class will be the super of t.
t = t or {}
t.__class = self
setmetatable(t, getmetatable(self))
return t
end
return class
Example code:
Code: Select all
-- class initialization
class = require('class')
-- Create vector class
Vector = class:new()
function Vector:init(x, y)
self.x = x or 0
self.y = y or 0
return self
end
function Vector:__add(vector2)
return self.__class:new(self.x + vector2.x, self.y + vector2.y)
end
function Vector:__tostring()
return "("..self.x..", "..self.y..")"
end
-- Example code
local vector1 = Vector:new(1, 1)
local vector2 = Vector:new(2, 3)
local newvector = vector1 + vector2
print(newvector)
Rectangle = Vector:subclass()
function Rectangle:init(x, y, width, height)
Rectangle.__class.init(self, x, y)
self.width = width
self.height = height
return self
end
function Rectangle:__add(rect2)
return self.__class:new(self.x + rect2.x, self.y + rect2.y, self.width + rect2.width, self.height + rect2.height)
end
function Rectangle:__tostring()
return "[("..self.x..", "..self.y.."), ".."("..self.width..", "..self.height..")]"
end
local rect1 = Rectangle:new(1, 1, 10, 10)
local rect2 = Rectangle:new(2, 3, 20, 20)
local rect3 = Rectangle:new(-5, -5, 10, 10)
local newrect = rect1 + rect2 + rect3
print(newrect)
Then run demo.
LoveObject.love
I'm not sure if I should make className a constant instead. Lua doesn't have contants.
