Re: Can an anonymous sub in a hash value know its key?

in reply to Can an anonymous sub in a hash value know its key?

My question is this: Is there a way that an anonymous sub stored as a hash value can have access to its associated key?

Unlike what several others have said, you can. In the code below, the anonymous sub gets the key belonging to the value passed in as its first argument.

#!/usr/bin/perl

use strict;
use warnings;

package Cute;

sub TIEHASH {bless {}, shift}
sub STORE   {my ($self, $key, $sub) = @_; 
             $$self{$key} = sub {$sub->($key)}}
sub FETCH   {${$_[0]}{$_[1]}}

package main;

tie my %hash, 'Cute';

my $greeting = sub {print "Hello, $_[0]\n"};

$hash{world} = $greeting;
$hash{earth} = $greeting;

foreach my $key (qw /world earth/) {
    &{$hash{$key}};
}
 
__END__
Hello, world
Hello, earth
[download]

Comment on Re: Can an anonymous sub in a hash value know its key? Download Code

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Re^2: Can an anonymous sub in a hash value know its key? by Tanktalus (Canon) on Mar 17, 2005 at 15:12 UTC
I like the package name. I think the lesson to be learned from this is that, with tie, the counterintuitive can be made to work! :-)	[reply]
Re^2: Can an anonymous sub in a hash value know its key? by webengr (Pilgrim) on Mar 17, 2005 at 21:42 UTC
Very nice! That does exactly what I was thinking of. I only wish I had a prize to award! PCS I was recently asked, "Does your program know when it isn't running?"	[reply]

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