use Perl

• seems to be a bug (Score:1)

  by steph (4655) on 2007.09.21 2:43 (#57947) Journal

  looks like a bug to me. somehow the interpolation stops at the first # found.
  

  
  
  
  % steph@ape (/home/stephan) %
  % cat t1.px
  #! /usr/bin/perl

  my $qr = qr/f/;
  print qr/$qr[#]$qr/x;

  my $qr2 = qr/f/;
  print qr/[b]$qr2/x;

  % steph@ape (/home/stephan) %
  % perl -w t1.px
  (?x-ism:(?-xism:f)[#]$qr)(?x-ism:[b](?-xism:f))

 
  

  Reply to This

  • Re: (Score:1)

    by Aristotle (5147)

    No, it’s not really a bug. An unescaped hashmark always starts a comment in patterns where /x applies. If the hashmark were backslash, it would produce the result that Chris probably expected.

    There is a definite argument to make that it’s counterintuitive, though. Whitespace in character classes is significant even under /x, so one would expect comments (which are usually thought of as a special kind of ignorable whitespace) would not be allowed in the middle of a character class.
    • Re: (Score:1)

      by ChrisDolan (2855)

      If it's not a bug, then why does the following print "f" and not "1"?

      print "#f" =~ m/[#](f)/x;

      Or more to the point, if the "#" is a comment character, why is it not a syntax error for an unclosed "[]" group?
      • Re: (Score:1)

        by Aristotle (5147)

        Ack. Yeah, definitely a bug then. Seems different parts of the regex parser have different ideas of when they’re inside a comment, or something like that.

        Did you write to p5p?
        • Re: (Score:1)

          by ChrisDolan (2855)

          My first attempt, before posting this journal entry, vanished into the ether (in retrospect, probably because my ISP blocks port 22). I just re-submitted. Thanks for reminding me.