#! /usr/bin/perl
use warnings;
use strict;

use Benchmark qw{ cmpthese };

my $orig = 'Just another Perl hacker,' x 100;
my $str  = $orig;
my $char = 'r';
my $q    = quotemeta $char;

sub transliteration {
    my $count = eval "\$str =~ tr/$q//"
}

sub length_subst {
    my $count = length( $str =~ s/[^$q]//rg )
}

sub subst {
    my $count = $str =~ s/$q/$char/g
}

transliteration() eq length_subst() or die 'Different t-ls';
transliteration() eq subst()        or die 'Different t-s';
$orig eq $str or die 'Changed';

cmpthese(-3, {
   transliteration => \&transliteration,
   length_subst    => \&length_subst,
   subst           => \&subst,
});

__END__
                    Rate    length_subst           subst transliteration
length_subst      2833/s              --            -91%            -97%
subst            30244/s            968%              --            -70%
transliteration 102423/s           3515%            239%              --