Re: chained hash slices?

@h{@a} returns a list, so adding curly braces for slicing doesn't make sense at all:

use strict;
use warnings;
use Data::Dumper;

my %h = (
        a =>    {b => 1},
        c =>    {d => 2},
    );
my @a = qw(a c);

print Dumper @h{@a};
__END__
$VAR1 = {
          'b' => 1
        };
$VAR2 = {
          'd' => 2
        };
[download]

If you want to slice that list, slice the indexing array instead:

my %h = (
        a =>    {b => 1},
        c =>    {d => 2},
    );
my @a = qw(a b c);

print Dumper @h{@a[0, 2]};
[download]

Comment on Re: chained hash slices? Select or Download Code

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Re^2: chained hash slices? by ikegami (Patriarch) on Jun 03, 2008 at 06:40 UTC
None of the following exist, so the result should be a list with 6 undef. $h{a}{0} $h{a}{2} $h{b}{0} $h{b}{2} $h{c}{0} $h{c}{2}	[reply]
Re^3: chained hash slices? by moritz (Cardinal) on Jun 03, 2008 at 06:52 UTC
So it seems the OP wants chained slice-dereferencing braces to calculate a cross product. That would be very unlike anything perl does at the moment. I don't see how `@hash{@list}{@list}` could work without being horribly magical, inconsistent and counter-intuitive. `@hash{@list}` returns a list of hash references, not a hash. If you want to change that, you'd have to invent a syntax like `%hash{@list}`, which merges all the hash refs into a single hash, which can be sliced in turn. And then you'd have to find a good way to deal with duplicates in the new hash.	[reply] [d/l] [select]