Re: How can I access object data in a user defined sort cmp function?

in reply to How can I access object data in a user defined sort cmp function?

The <=> can dig into objects and hashes, so you can use something like $a->key->{'other'} <=> $b->key->{'other'}. Proof of concept:

#/usr/bin/perl
use warnings;
use strict;
use Data::Debug;

my @things;
push @things, Thing->new() for (1..10);
debug @things;
my @sorted = sort { $a->key->{'other'} <=> $b->key->{'other'} } @thing
+s;
debug @sorted;

package Thing;
sub new { return bless { key => { other => int(rand(42))} }, 'Thing'; 
+}
sub key { return shift->{'key'}; }
1;
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I hope that is helpful :)

Comment on Re: How can I access object data in a user defined sort cmp function? Download Code

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Re^2: How can I access object data in a user defined sort cmp function? by tkguifan (Scribe) on Jan 29, 2015 at 19:37 UTC
This is not the same thing. You are sorting the objects themselves rather than a hash stored within an object. This is a cheat because now $a and $b are object references, so they speak for themselves. If $a and $b are simply keys of a hash, the sort function has no clue to what object they belong. However it is true, as others pointed out, that if I write the compare function in-line instead of a separate function, the in-line code sees the variables of the sub ( including the $self with which it was called ), so it has access to the object.	[reply]

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Re^2: How can I access object data in a user defined sort cmp function?
by tkguifan (Scribe) on Jan 29, 2015 at 19:37 UTC

This is not the same thing. You are sorting the objects themselves rather than a hash stored within an object. This is a cheat because now $a and $b are object references, so they speak for themselves. If $a and $b are simply keys of a hash, the sort function has no clue to what object they belong. However it is true, as others pointed out, that if I write the compare function in-line instead of a separate function, the in-line code sees the variables of the sub ( including the $self with which it was called ), so it has access to the object.

[reply]

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