Re: A function to create an object using closures

[Matthew Paul Del Buono <delbu9c1@...>]

Hi Michal,

>function Greeting()
>local self = {}
>-- Private attributes and methods
>local message = "Good morning"
>-- Public methods
>self.get = function() return message end
>self.say = function() print(self.get()) end
>return self
>end

I disagree with this here. If you're only creating one Greeting object or only a few, it might be okay, but I think that if you create many, you're going to have an issue with memory.

Generally a metatable is used in the following form:

Greeting = {};
Greeting.__index = Greeting;

function Greeting.new(message)
   local self = setmetatable({}, Greeting);
   self._message = message;
   return self;
end

function Greeting:get()
   return self._message;
end

function Greeting:say()
   print(self._message);
end


However, there are valid uses for what you specified as well. Both will work; it's up to what you want to do, really. Personally, I'm generally more pressed for memory, so I prefer the metatable approach for frequently used cases.

Regards,
-- Matthew P. Del Buono