> From: "Brent Dax" <[EMAIL PROTECTED]>
> Date: Thu, 5 Dec 2002 00:28:52 -0800
>
> Michael G Schwern:
> # You can do it with a map without much trouble:
> #
> # my @indexes = map { /condition/ ? $i++ : () } @stuff;
>
> Unless I'm mistaken, that won't work, since $i only gets incremented on
> matches. I think this:
>
> my @indexes = map { $i++; /condition/ ? $i : () } @stuff;
>
> Will work fine, though.
> Or, in the spirit of use-a-foreach-like-a-for (and my favorite WTDI):
>
> my @indexes = grep { $stuff[$_] =~ /condition/ } 0..$#stuff;
Fantastic! One that doesn't use a variable temporary variable. We
all write too quickly to catch errors like the one above. Except
yours seems to be clean. Anyway---back to relevant topics.
> As you might guess, I'm a (not very vocal) proponent of adding a way to
> get at a foreach's (or map's or grep's) current index. (Hmm, can this
> be done with XS? Must research...)
In Perl 5 that would be nice. In Perl 6 though, it is not necessary:
for zip(@array, 0..Inf) -> $v, $c {
...
}
That parallel iteration is just getting more and more useful (although
this is a particularly ancient case). We've already been through A4,
but the idea of C<for> has changed since then (I think). I don't like
C<zip> as a name for such a thing.
for interleave(@array, 0..Inf) {...}
Too long.
for slice (@array, 0..Inf) {...}
for collate (@array, 0..Inf) {...}
for parallel(@array, 0..Inf) {...}
for braid (@array, 0..Inf) {...}
for thread (@array, 0..Inf) {...}
for weave (@array, 0..Inf) {...}
The sequential list generator would almost certainly be C<each>, if we
need one at all.
for @array {...}
for each @array: {...}
for each(@array, @barry) {...}
for @array, @barry {...} # Is this legal?
That last one might iterate through the arrays themselves, not their
elements, which would be useful on the blue moon nights. ??
Or is it still:
for @array ; 0..Inf -> $v ; $c { ... }
I hope not.
Not to delay the next Apocalypse, or anything <:(
Luke
