Re: upcoming changes in Lua 5.2 [was Re: Location of a package]

[Ignacio Burgueño <ignaciob@...>]

Jérôme Vuarand wrote:
> 2008/2/19, Roberto Ierusalimschy <roberto@inf.puc-rio.br>:
> > > Roberto, is there any description of upcoming changes in Lua 5.2?
> >  There is no "official" roadmap :) The following is a list of what we
> >  have been doing.
> >
> >  We have already implemented several small changes:
> >
> >  [...]
> >
> >  - "metamethods" __pairs & __ipairs
>
> Why is the new ipairs using an __ipairs metamethod rather than the
> existing __index ?

First, I think that the above would be a very welcomed addition to Lua.
Second, in my opinion, __index and __ipairs (whatever the final 
semantics may be) are not comparable. __index is triggered on access to 
non-existent keys and __ipairs would be used to redefine the way an 
array-like table is iterated, right?

Also, using the same metamethod for both cases will make it hard to 
distinguish when you're indexing a table and when you're going to 
iterate it.

Regards,
Ignacio Burgueño