In a message dated Fri, 9 Aug 2002, Adam Lopresto writes:
> I was wondering whether the Perl 'while (<>){' idiom will continue to be
> supported in Perl 6? I seem to recall people posting example code the list
> using it (although I can't dig any up), but it seems to me that if Perl 6's
> lazy list implementation is sufficiently smart, it could just be replaced with
> 'for <> {'. The only issues I can see are people using <> inside the loop, and
> maybe something about the scope of $_. (Does a topicalized $_ change the value
> of $_ outside of the loop?)
>
for <> { ... }
will be the new idiom, and it will be completely regular: a lazy iteration
of a list, with implicit topicalization to $_.
while <> {...}
Might be supported as a special case, I haven't heard either way. But by
switching while to for, no special syntactic sugar is necessary, unlike in
previous Perls.
I don't see why one couldn't use <> inside the for look. Either it's the
same iterator inside and out (iterators associated with filehandles), in
which case it'll do the right thing, or it's a different iterator
(iterators scoped by block), in which case the inside lazy iterator will
be monkeying with stuff that the outside lazy iterator has never, and will
never, see.
I don't know which it is, but either way, it seems like it would work fine
in the case of a filehandle read (provided that iterators can look ahead
and put stuff back on the buffer, which I understand they will be able
to).
Trey
