I wrote once or twice to the Lua mailing list asking for OOP support in the language. I understand that metatables can be used to fake the OO paradigm in Lua, but there are some problems with them.
One big problem in my opinion is when you use many Lua libraries developed by others. If each use their own OOP library you end up with different ways to do the same thing, i.e. to instantiate one object from a class in one library you use "obj = Class.new()", to do the same thing with a class from another library you use "obj = Class:Create()"...
As OOP is such an useful feature to have, what people think about having a love.oop library, blessed by Löve developers? What features do you need from such a library? Mine are:
1. Don't look cryptic
2. Allow the calling of inherited methods
3. Allow multiple inheritance
4. Be lightweight, i.e. do not perform tons of work when I call a method, ideally just one table lookup to get the method
5. Have an "instanceof" function just like the Java operator with the same name
It should look similar to this:
Code: Select all
local Image = class()
function Image:new( filename )
...
end
local Sprite = class( Image )
function Sprite:new( filename )
Image.new( self ) -- inherited method call (constructor in this case)
...
end
local hero = Sprite( 'hero.png' ) -- calls new with a newly created instance
Polymorphism comes for free as Lua is dynamically typed. An object can be anything, and if it's not the right type, you'll get an error sooner or later: attempt to call method 'xxx' (a nil value)
Hope this helps mager1794 in his efforts and we end up with an OOP library to rule them all...
Cheers,
Andre
