#!/usr/bin/perl
use Benchmark qw/cmpthese/;

$defaulttext = q/foo / x 30;
# $defaulttext = q/foobar / x 30;

cmpthese( 100_000, {
    slash_b => q{$text=$defaulttext; $text =~ s/\bfoo\b//g;},
    neg_look=> q{$text=$defaulttext; $text =~ s/(?<!\w)foo(?!\w)//g;},
    pos_look=> q{$text=$defaulttext; $text =~ s/(?<=[^\w])foo(?=[^\w])//g;},
});
##</code><code>##

          Rate    pos_look  neg_look  slash_b
pos_look 27894/s     --        -8%     -35%
neg_look 30441/s     9%         --     -29%
slash_b  42662/s    53%        40%      --

##</code><code>##

$text= q/foo bar foo/;
($tmp = $text) =~ s/\bfoo\b//g;
print $tmp,"\n";

($tmp = $text) =~ s/(?<!\w)foo(?!\w)//g;
print $tmp,"\n";

($tmp = $text) =~ s/(?<=[^\w])foo(?=[^\w])//g;
print $tmp,"\n";

# which prints:
 bar
 bar
foo bar foo