Re: Re^2: Never (qr//)

[grantm]

You're right, publishing a benchmark without the test data is pretty meaningless. Here's a revised version that uses the individual words output from 'perldoc -t perlfunc' as the test data.

#!/usr/local/bin/perl -w

use Benchmark;

my (@words, $count);
open(TESTDATA, "perldoc -t perlfunc|") || die $!;

while(<TESTDATA>) { chomp; push @words, /(\S+)/g }

print @words . " words\n";

my $alpha = '[a-zA-Z]';
my $alnum = '[a-zA-Z0-9]';
my $qr    = qr/^$alpha$alnum+$/;

timethese(100, {
   '/^$alpha$alnum+$/ ' => \&testsub,
   '/^$alpha$alnum+$/o' => \&testsubo,
   '/$qr/             ' => \&testsubqr1,
   '$qr               ' => \&testsubqr2,
   '/$qr/o            ' => \&testsubqro,
});

sub testsub    { foreach (@words) { $count++ if(/^$alpha$alnum+$/);  }
+ }

sub testsubo   { foreach (@words) { $count++ if(/^$alpha$alnum+$/o); }
+ }

sub testsubqr1 { foreach (@words) { $count++ if(/$qr/);              }
+ }

sub testsubqr2 { foreach (@words) { $count++ if($_ =~ $qr);          }
+ }

sub testsubqro { foreach (@words) { $count++ if(/$qr/o);             }
+ }

This is probably a fairer test than the original (less iterations of more data) and the output looks like this:

/^$alpha$alnum+$/ : 20 wallclock secs (20.41 usr +  0.00 sys = 20.41 C
+PU) @  4.90/s (n=100)
/^$alpha$alnum+$/o:  9 wallclock secs ( 8.34 usr +  0.00 sys =  8.34 C
+PU) @ 11.99/s (n=100)
/$qr/             :  9 wallclock secs ( 9.59 usr +  0.00 sys =  9.59 C
+PU) @ 10.43/s (n=100)
$qr               : 10 wallclock secs ( 9.94 usr +  0.00 sys =  9.94 C
+PU) @ 10.06/s (n=100)
/$qr/o            :  9 wallclock secs ( 8.34 usr +  0.01 sys =  8.35 C
+PU) @ 11.98/s (n=100)

The reason I used /$qr/ rather than =~ $qr was not because I didn't know how to use it, but because I was using it in an if statement and $qr being a reference would simply evaluate to true without even attempting a match. The results above appear to show that plain $qr is slightly slower than /$qr/ but that is almost certainly due to the fact that I had to spell it out as $_ =~ $qr and so the difference should be disregarded.

[BrowserUk]

There is also the problem with using the =~ $qr form that you cannot use it if you need to apply the /g option.

Nor if you have a regex that you sometimes want to use with capturing and sometimes without.

Nor can you use it in substitutions.

---

Examine what is said, not who speaks.
"Efficiency is intelligent laziness." -David Dunham
"When I'm working on a problem, I never think about beauty. I think only how to solve the problem. But when I have finished, if the solution is not beautiful, I know it is wrong." -Richard Buckminster Fuller