That's becauase this is a closure and $count retains its value between calls, since there is actually an instance of $count being carried around in the coderef.

Either move $count into the outer scope, so you can clear it between calls, or generate a new set closures, modding the previous poster's code Re: Closures and sort :

use strict;

my @list = qw/ box cow dog apple ant/;

sub mksub
{
    my $count = 0;

    my $s1 = sub  { return $count }; # an inspector as a closure

    # and another closure
    my $s2 = sub
    {
        $count++;
        return $_[0] cmp $_[1];
    };

    return ( $s1, $s2 );
}

my ( $get_count, $compare, );
( $get_count, $compare, ) =  mksub();
print sort { $compare->( $a, $b ) } @list;
print "\n";
print $get_count->(), "\n";
print "\n";

print sort { $compare->( $a, $b ) } @list;
print "\n";
print $get_count->(), "\n";
print "\n";

( $get_count, $compare, ) =  mksub();
print sort { $compare->( $a, $b ) } @list;
print "\n";
print $get_count->(), "\n";
print "\n";
[download]

Which produces:

antappleboxcowdog
9

antappleboxcowdog
18

antappleboxcowdog
9

Update: as someone else said, creating a reset_count coderef inside the same scope would do this and be cleaner than what I did.

--Bob Niederman, http://bob-n.com