Re: Speed of Perl Regex Engine

[Jenda]

in reply to Speed of Perl Regex Engine

You said you build the regex and pass it to the program as a parameter ... how do you use it then?

 my $regexp = @ARGV[1];
 ...
 next if ($global =~ /$regexp/);
 ...

 my $regexp = @ARGV[1];
 ...
 next if ($global =~ /$regexp/o);
 ...

 my $regexp = qr/@ARGV[1]/;
 ...
 next if ($global =~ $regexp);
 ...

The first version compiles the regexp each time you use it, the other two just once. For a longer regexp this may make a big difference.

[runrig]

I believe in later versions of Perl (>= 5.6), this is no longer true. As long as $regexp doesn't change, /$regexp/ isn't compiled again, making "/o" (mostly) obsolete.