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Re^2: Perlplexation - foreach shoulda Known (Rosetta: Perl, Python, Ruby)

by eyepopslikeamosquito (Bishop)
on Apr 13, 2012 at 21:51 UTC ( #965000=note: print w/replies, xml ) Need Help??

in reply to Re: Perlplexation - foreach shoulda Known
in thread Perlplexation - foreach shoulda Known

Is there a special variable that tracks what $i is tracking in that example?
Curiously, this is very easy in Python:
x = [ 'apple', 'banana', 'orange' ] for i, val in enumerate(x): print i, val
which prints:
0 apple 1 banana 2 orange
and fairly easy in Ruby:
x = [ 'apple', 'banana', 'orange' ] x.each_with_index { |val, i| print "#{i} #{val}\n" }
and I'm sure (need to wait for moritz to show me how) it's easy in Perl 6 too (probably via Array kv and/or pairs methods?).

I was hoping List::Util or List::MoreUtils might have something nice, but the best I could find is to use an iterator like so:

use List::MoreUtils qw(each_array); my @x = ( 'apple', 'banana', 'orange' ); my $it = each_array( @{[0..$#x]}, @x ); while ( my ($i, $val) = $it->() ) { print "$i $val\n"; }
which is horrific. Is there a better way in List::Util or List::MoreUtils that I missed?

While I was writing this, chromatic showed how to do it in Perl 5.12 or above:

my @x = ( 'apple', 'banana', 'orange' ); while ( my ($i, $val) = each @x ) { print "$i $val\n"; }

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Re^3: Perlplexation - foreach shoulda Known
by MonkOfAnotherSect (Sexton) on Apr 18, 2012 at 06:47 UTC
    eyepopslikeamosquito writes:
    Curiously, this is very easy in Python...
    And Riales's task too: remember -- slices win ;-)
    for elem in some_iterable[::3]: do_something(elem)
    Then again, I'd argue that it's really not so curious given how much iteration support/use/avoidance is baked-in (iterator and sequence protocols, generators, comprehensions, slices, etc).

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