#!/usr/bin/perl
use strict;
use warnings;
use Benchmark qw( cmpthese );

cmpthese -2, {
   by_substr => sub {
      my $nomedir = '20070502-11';
      my $anno        = substr $nomedir, 0, 4;
      my $mese        = substr $nomedir, 4, 2;
      my $giorno      = substr $nomedir, 6, 2;
      my $progressivo = substr $nomedir, 9, 2;
   },
   by_unpack => sub {
      my $nomedir = '20070502-11';
      my ($anno, $mese, $giorno, $progressivo)
         = unpack 'A4 A2 A2 x A2', $nomedir;
   },
};
poletti@PolettiX:~/sviluppo/perl$ /opt/perl-5.8.8/bin/perl numstat.pl
              Rate by_unpack by_substr
by_unpack 417553/s        --      -32%
by_substr 613303/s       47%        --
poletti@PolettiX:~/sviluppo/perl$ /opt/perl-5.10.0/bin/perl numstat.pl
              Rate by_unpack by_substr
by_unpack 372754/s        --      -34%
by_substr 565358/s       52%        --
poletti@PolettiX:~/sviluppo/perl$ /opt/perl-5.8.8/bin/perl numstat.pl
              Rate by_unpack by_substr
by_unpack 415531/s        --      -33%
by_substr 616325/s       48%        --
poletti@PolettiX:~/sviluppo/perl$ /opt/perl-5.10.0/bin/perl numstat.pl
              Rate by_unpack by_substr
by_unpack 374480/s        --      -33%
by_substr 562716/s       50%        --
poletti@PolettiX:~/sviluppo/perl$ /opt/perl-5.8.8/bin/perl numstat.pl
              Rate by_unpack by_substr
by_unpack 415531/s        --      -33%
by_substr 616325/s       48%        --
poletti@PolettiX:~/sviluppo/perl$ /opt/perl-5.10.0/bin/perl numstat.pl
              Rate by_unpack by_substr
by_unpack 369821/s        --      -34%
by_substr 562716/s       52%        --