Re: Where Tcl and Tk went wrong; {SPAM?} Re: Where Tcl and Tk went wrong

[Aleirade <aleirade@...>]

--------- Mensagem Original --------
De: Lua list <lua@bazar2.conectiva.com.br>
Para: Lua list <lua@bazar2.conectiva.com.br>
Assunto: Re: Where Tcl and Tk went wrong; {SPAM?} Re: Where Tcl and Tk went
wrong
Data: 01/04/10 06:32

> On Thu, Apr 1, 2010 at 12:18 AM, Vaughan McAlley <ockegheim@gmail.com>
wrote:
> > Do you mean when objects of different schemes try to talk to each
> > other?
> 
> Specifically when you try to inherit from a 'class' that is
> implemented by a different scheme. ('class' in quotes because the
> concept is not basic to Lua)
> 
> > newObject = setmetatable( {}, { __index = parentObject })

Sure, but it isn't readable nor efficient. And those are important things in
a language to use in gameplay scripts, in which Lua fits (almost) nicely.

Andre

> That's one scheme; your class is a metatable, which has a 'fallback'
> __index pointing at the parent class, giving you an inheritance chain.
> This can hurt performance, so there's also 'fat metatable' inheritance
> where the base class members are copied into the metatable.  Classes
> get a little fatter, but assuming that there are many more objects
> than classes this is a fine trade-off.
> 
> If the number of objects of a given class are small, then
> closure-based classes are faster but you pay more per object.
> 
> But if the 'class' is a metatable, then the inheritance chaining
> method should work with it.
> 
> steve d.
> 
> http://lua-users.org/wiki/LuaClassesWithMetatable
> 
> 

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