in reply to Are perlfaq6 and perlop correct about "/o" modifier?

First, I removed the incorrect /c which totally breaks the benchmark.

Then I added a qr-using solution since one might argue that it's qr that "obsoletes /o". 

use strict;
use warnings;
use feature 'say';
use Benchmark 'cmpthese';

my $pat = qr/\d+/;
my $s = '123abc' x 1e6;
my $re = qr/\G $pat \D+ /x;

cmpthese -1, {
    "o=0" => sub { 1 while $s =~ /\G $pat \D+ /gx  },
    "qr"  => sub { 1 while $s =~ /$re/g            },
    "o=1" => sub { 1 while $s =~ /\G $pat \D+ /gxo },
};

[download]
      Rate  o=0   qr  o=1
o=0 3.12/s   --  -8% -59%
qr  3.39/s   8%   -- -55%
o=1 7.55/s 142% 123%   --

[download]

...and we still get a large divide. Your point remains, but it now has a valid foundation.

Note that /o is only 140% faster and not 750% faster. That's probably because of your /c bug.

Replies are listed 'Best First'.
Re^2: Are perlfaq6 and perlop correct about "/o" modifier?
by Anonymous Monk on May 09, 2026 at 17:46 UTC
    Note that /o is only 140% faster and not 750% faster.

    I ran this under a few versions of Perl and /o is 200% faster with 5.42.0 because qr and o=0 are slower!

    5.42.0: 

          Rate  o=0   qr  o=1
o=0 4.17/s   -- -14% -67%
qr  4.85/s  17%   -- -61%
o=1 12.5/s 200% 158%   --
    5.38.2: 
          Rate  o=0   qr  o=1
o=0 5.22/s   -- -17% -58%
qr  6.31/s  21%   -- -50%
o=1 12.5/s 140%  98%   --
    5.16.3: 
          Rate  o=0   qr  o=1
o=0 8.26/s   --  -4% -38%
qr  8.57/s   4%   -- -36%
o=1 13.4/s  62%  56%   --
[reply]

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