Re: How can I learn about Object Oriented programming with lua?

[Steve Litt <slitt@...>]

Is this available in a format that doesn't word-wrap?

Thanks,

SteveT

On Thu, 27 Feb 2014 13:33:14 +0100
Wouter Scherphof <wouter.scherphof@gmail.com> wrote:

> The below snippet from Luvit might be pretty much all OO you ever
> really need.
> 
> 2014-02-23 3:19 GMT+01:00 Journeyer J. Joh <oosaprogrammer@gmail.com>:
>  | What method would be the best for OO style lua programming?
> 
> 
> --[[
> This is the most basic object in Luvit. It provides simple prototypal
> inheritance and inheritable constructors. All other objects inherit
> from this. ]]local Object = {}
> core.Object = Object
> Object.meta = {__index = Object}
> -- Create a new instance of this objectfunction Object:create()
>   local meta = rawget(self, "meta")
>   if not meta then error("Cannot inherit from instance object") end
>   return setmetatable({}, meta)end
> --[[
> Creates a new instance and calls `obj:initialize(...)` if it exists.
> 
>     local Rectangle = Object:extend()
>     function Rectangle:initialize(w, h)
>       self.w = w
>       self.h = h
>     end
>     function Rectangle:getArea()
>       return self.w * self.h
>     end
>     local rect = Rectangle:new(3, 4)
>     p(rect:getArea())
> ]]function Object:new(...)
>   local obj = self:create()
>   if type(obj.initialize) == "function" then
>     obj:initialize(...)
>   end
>   return objend
> --[[
> Creates a new sub-class.
> 
>     local Square = Rectangle:extend()
>     function Square:initialize(w)
>       self.w = w
>       self.h = h
>     end
> ]]
> function Object:extend()
>   local obj = self:create()
>   local meta = {}
>   -- move the meta methods defined in our ancestors meta into our own
>   --to preserve expected behavior in children (like __tostring,
> __add, etc) for k, v in pairs(self.meta) do
>     meta[k] = v
>   end
>   meta.__index = obj
>   meta.super=self
>   obj.meta = meta
>   return objend
> 
> Plus maybe this, also from Luvit:
> 
> --[[
> Returns whether obj is instance of class or not.
> 
>     local object = Object:new()
>     local emitter = Emitter:new()
> 
>     assert(instanceof(object, Object))
>     assert(not instanceof(object, Emitter))
> 
>     assert(instanceof(emitter, Object))
>     assert(instanceof(emitter, Emitter))
> 
>     assert(not instanceof(2, Object))
>     assert(not instanceof('a', Object))
>     assert(not instanceof({}, Object))
>     assert(not instanceof(function() end, Object))
> 
> Caveats: This function returns true for classes.
>     assert(instanceof(Object, Object))
>     assert(instanceof(Emitter, Object))
> ]]function instanceof(obj, class)
>   if type(obj) ~= 'table' or obj.meta == nil or not class then
>     return false
>   end
>   if obj.meta.__index == class then
>     return true
>   end
>   local meta = obj.meta
>   while meta do
>     if meta.super == class then
>       return true
>     elseif meta.super == nil then
>       return false
>     end
>     meta = meta.super.meta
>   end
>   return falseend