The problem I have with state is that I usually don't want the variable to be set only once, but only once for a given part of the data . It behaves this way only in anonymous subs, because you declare a new sub for each iteration. Cf. 
#! /usr/bin/perl
use warnings;
use strict;
use feature 'state';

sub frobnicate {
    state $f = 0;
    $f += shift;
    $f
}

my @data = ( [ 1, 1, 1 ],
             [ 1, 2, 3 ],
             [ 4, 4, 4 ],
);

for my $block (@data) {
    my $block_result = 0;
    for my $element (@$block) {
        $block_result = frobnicate($element);
    }
    print $block_result, "\n";
}

print "Versus\n";

for my $block (@data) {
    my $frobnicate = sub {
        state $f = 0;
        $f += shift;
        $f
    };
    my $block_result = 0;
    for my $element (@$block) {
        $block_result = $frobnicate->($element);
    }
    print $block_result, "\n";
}

[download]

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re: state is the root of evil? by choroba
in thread state is the root of evil? by basiliscos

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