Simple Inheritance Of Lua

A lua version like JR's simple-inheritance in javascript

By fanxl

http://www.hippyless.com/blog/?p=9

MIT Licensed

Example

Base Object

BaseObject = Class:extend({

	__className = "BaseObject",
	
	init = function(self)
		print("BaseObject init")
	end,
	
	info = function(self)
		print("BaseObject info")
	end
	
})

Extend BaseObject

FlyObject = BaseObject:extend({
   
    __className = "FlyObject",
	
	init = function(self,speed)
	    self.speed  = speed;
		self:_super() --super init method
		print("FlyObject init")
	end,
	
	fly = function(self)
		print("FlyObject fly with speed"..self.speed)
	end	
})

Override

DuckObject  = FlyObject:extend({
    
    __className = "DuckObject",
    
	init = function(self,speed,sound)
		self:_super(speed)
		self.sound = sound
		print("DuckObject init")
	end,

	fly = function(self) --override FlyObject
		self:_super()
		print("DuckObject fly with speed"..self.speed)
	end,
	
	info = function(self)  --override BaseObject
		self:_super()
		print("DuckObject info")
	end,
	
	sound = function(self)
		return self.sound
	end
})

Runtime type check

liveduck = DuckObject:new(500,"gaga~gaga~")
print("live duck is  instance of DuckObject? "..tostring(liveduck:instanceof(DuckObject)))
print("live duck is  instance of FlyObject? "..tostring(liveduck:instanceof(FlyObject)))
print("live duck is  instance of BaseObject? "..tostring(liveduck:instanceof(BaseObject)))