There is not a noticeable increase in speed in using $x = qr/.../; /$x/ instead of $x = '...'; /$x/o; in the testing I have done. And the /o modifier is ONLY useful if the regex has any variables in it.

The place where qr// is important is when looping over strings and patterns. If you do a benchmark of code like this: 

while (<>) {
  for my $p (qr/a+b/, qr/c+d/, qr/e+f/) { foo() if /$p/ }
}

# vs.

while (<>) {
  for my $s ('a+b', 'c+d', 'e+f') { foo() if /$s/ }
}

[download]
The qr// version will be considerably faster because Perl knows the regexes are already compiled, whereas in the string version, we need to compile three regexes for every line of input.

_____________________________________________________
Jeff[japhy]Pinyan: Perl, regex, and perl hacker, who'd like a job (NYC-area)
s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;

In reply to Re: /o is dead, long live qr//! by japhy
in thread /o is dead, long live qr//! by diotalevi

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