|
Re: foreach count variable
by rob_au (Abbot) on Nov 18, 2002 at 21:42 UTC
|
As it is, there is currently no implicit variable available to serve your purpose - There was the proposal of such a variable made in RFC120 and RFC262 for Perl 6 but this has been rejected by Larry - See Apocolypse 4, specifically here and here.
The only way to implement such a counter is to loop by index, rather than value - For example:
foreach my $count ($[..$#bar) {
print $count, " -> ", $bar[$count], "\n";
}
Not quite as pretty or flexible, but the introduction of implicit loop variables would also mean the introduction of additional construct overhead.
perl -e 'print+unpack("N",pack("B32","00000000000000000000000111100100")),"\n"' | [reply]
[d/l] |
Re: foreach count variable
by Zaxo (Archbishop) on Nov 18, 2002 at 21:34 UTC
|
my $bar = join $/, @bar;
$bar .= $/;
open my $foo, '<', \$bar or die $!;
while (<$foo>) {
print $., ' -> ', $_;
}
close $foo or die $!;
That will take perl 5.8 to work. Yes, it's much heavier than $count++, but it's a window into a whole 'nother thing. (Added shameless plug) See Open Has a New Trick.
After Compline,
Zaxo
| [reply]
[d/l] |
Re: foreach count variable
by BrowserUk (Patriarch) on Nov 18, 2002 at 21:45 UTC
|
for my $count (0..$#bar) {
print $count . "-> " . $bar[$count];
}
In someways better than using for my $thing (@array){...} as n..m evaluates its list lazily, so doesn't build a huge list from @array just to consume it one thing at a time.
Okay you lot, get your wings on the left, halos on the right. It's one size fits all, and "No!", you can't have a different color.
Pick up your cloud down the end and "Yes" if you get allocated a grey one they are a bit damp under foot, but someone has to get them.
Get used to the wings fast cos its an 8 hour day...unless the Govenor calls for a cyclone or hurricane, in which case 16 hour shifts are mandatory.
Just be grateful that you arrived just as the tornado season finished. Them buggers are real work. | [reply]
[d/l]
[select] |
Re: foreach count variable
by gjb (Vicar) on Nov 18, 2002 at 21:32 UTC
|
Okay, many are going to flame me, but this looks like an excellent occasion to use a C-type loop:
for (my $count = 0; $count < scalar(@bar); $count++) {
printf "%d -> %s\n", ($count, $bar[$count]);
}
Awaiting your scorn, -gjb-
| [reply]
[d/l] |
|
|
You needn't flinch, there's nothing wrong with that.
An alternative is:
my @foo = qw(one two three four);
for (0..$#foo) {
print "$_ : $foo[$_] \n";
}
Andy.
| [reply]
[d/l] |
|
|
yeah, thats the other way doing it.
but still too much keys to press,
and it looks quite 'untidy' :-)
| [reply] |
|
|
Your idea is fine, but the execution could be better.. :) There's no need for scalar nor printf there.
for (my $count = 0; $count < @bar; $count++) {
print "$count -> $bar[$count]\n";
}
But then, I'd still prefer the for(0 .. $#bar) form proposed further down the thread.
Makeshifts last the longest. | [reply]
[d/l] |
Re: foreach count variable
by dreadpiratepeter (Priest) on Nov 19, 2002 at 05:10 UTC
|
I've also always wanted that feature. Sometimes you want both the element and the position at the same time.
I talked to Damian and Dan about it at the Perl conference year before last and they liked my suggestion (for Perl6) but I guess nothing ever came of it.
I proposed an attribute on the topic (list variable), ie:
foreach my $foo qw(a b c d e f g) {
print $foo,$foo.index;
}
Although I'm not sure that index is the best name for the attribute. Maybe position?
-pete
"Worry is like a rocking chair. It gives you something to do, but it doesn't get you anywhere." | [reply]
[d/l] |
|
|
yep. in perl6 this attribute would be nice.
there is even one more way to go:
foreach my $foo (@bar) count $c {
print $c . "-> " . $foo;
}
or maybe:
foreach my $foo (@bar) counting $c {
print $c . "-> " . $foo;
}
| [reply]
[d/l]
[select] |