Re: Next Lua (5.2) feature request : slicing

[Mildred <ml.mildred593@...>]

Le mar 21/11/2006 à 23:53 Mike Pall à écrit:
> Hi,
> 
> Mildred wrote:
> > Why do not add slicing in the next release of Lua ?
> > [...]
> > Any toughts about it ?
> 
> http://lua-users.org/lists/lua-l/2004-11/msg00083.html
> 
> Bye,
>      Mike
> 

Maybe it is possible without adding new opcodes.
IO was just thinking that actually, the [] syntax accept only one value
and that it could be possible to put multiples values in there. And
then, the default behaviour would be :
- for tables to extract a part of it
- if the __index metamethod is defined, just give the multiples
values as parameter

Ahd the tab[x:y] syntax would simply be syntaxic shugar for tab[x,y].

It seems very light to me. The idea is just to add support for
multiples values in the [] and do something useful with them. But I
don't know lua internals, so maybe it is not. But I think, if it is
easy to do, why not have it ?

Also, in my post, there was something else, indexing strings by default
(change metatable). To be able to do ("abc")[2].
Speaking about strings, I think slicing is much more useful with string
than with tables, so it is a good idea to have it. You can see that
we have a string.sub but no table.sub function :)

The problem with that solution is that slicing assigment is not
possible. Something like a[1:3]=b[2:4], but I don't think it is very
used. And it is still better to have basic slicing than nothing.

-- 
Mildred       <xmpp:mildred@jabber.fr> <http://mildred632.free.fr/>
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