Hash usage question

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I ran across this sample while reading an article by Chromatic:

my @fields = qw( name email );
my %results;
@results{@fields} = ();
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I mean I see what happens here:

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

my @fields = qw( name email );
my %results;
print "Before: ", Dumper(\%results);
@results{@fields} = ();
print "After: ", Dumper(\%results);

__END__

Before: $VAR1 = {};

After: $VAR1 = {
          'email' => undef,
          'name' => undef
        };
[download]

I'm just not sure why it works. How does @results resolve to %results? Apparently the use of {} must force some context since normally @results and %results refer to different variables. Thanks.

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Replies are listed 'Best First'.
Re: Hash usage question by Enlil (Parson) on May 23, 2003 at 23:24 UTC
perldata has a good intro to slices. Which right near the end of the slice section your question is answered. :) -enlil	[reply]
Re: Hash usage question by chromatic (Archbishop) on May 24, 2003 at 00:34 UTC
You're right; it is indeed the subscripting punctuation that clarifies whether it's an array or a hash. In Perl 5, the leading sigil signifies what you want out of the data structure -- a scalar, a list, or a hash. In Perl 6, the leading sigil will remain constant, and context will determine what you get out of it.	[reply]