Minor Disaster

grep

        my $pat = shift;

        while (<>) {
          print if /$pat/;
        }

• Here the pattern does not vary at runtime

• Perl still checks each time to see if it has changed

        my $pat = shift;

        while (<>) {
          print if /$pat/o;
        }

• /o modifier promises that the pattern will never change

• Perl no longer needs to check

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Copyright © 2002 M. J. Dominus