SeekerOKnowledge has asked for the wisdom of the Perl Monks concerning the following question:

I have working regex's which substitute errant fonts in Framemaker .mif files to something more agreeable to our tech writers. ie. 
my $pattern = qr{<PgfTag `Normal \(T\)'>\s*\n\s*<ParaLine\s*\n\s*<Stri
+ng `$oldLabel'>\s*\n};
my $replacement = "<PgfTag `Block Label \(T\)'>\n<ParaLine\n<String `$
+newLabel'>\n";
my $k = 0;
$$contents =~ s/$pattern/++$k && $replacement/ge;

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What I would like to do is reformat & comment these regex's more in the style discussed in perlfaq6. Yet when I break the qr// statement up into multiple lines, I no longer match correctly. Is there a way to do this?

Thanks for any insight you can pass along!

j

Replies are listed 'Best First'.
Re: commenting regular expressions?
by herveus (Prior) on Sep 04, 2003 at 18:02 UTC
    Howdy!

    Did you use the /x modifier?

    I see white space in your regexes. If you use /x, you have to escape the white space or it gets ignored.

    For example (untested): 

    qr{<PgfTag
   [ ]   # this matches a space
   'Normal
   \  # the backslash ought to escape the space
   \\(T\)'>
...

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    and so forth...

    yours,
    Michael

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[d/l]
      I had played with the following to no avail: 
      #!/usr/bin/perl

my $s = "blah,blah,blah <PgfTag `Normal \(T\)'> yadda,yadda,yadda";
print "s =\t\"$s\"\n";

my $pattern = qr{
    \s*
        <PgfTag `Normal \(T\)'>
    \s*
};

my $k = 0;

$s =~ s/$pattern/++$k && ','/gex;

print "$k change(s)\n";
print "s =\t\"$s\"\n";

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[d/l]
        You have to put /x on the expression when you declare it. Also, as said, escape the literal spaces in the tags, or use \s if you don't mind matching any whitespace. 
        my $pattern = qr{
    <PgfTag\ `Normal\ \(T\)'> 
    \s* \n
    \s* 
    <ParaLine 
    \s* \n
    \s*
    <String\ `$oldLabel'> 
    \s* \n
   }x;

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[d/l]
Re: commenting regular expressions?
by ajdelore (Pilgrim) on Sep 04, 2003 at 17:58 UTC

    You need to add the /x modifier to your regexes.

    Updated: as pointed out by a couple of others, you need to add it to each qr{...}x statement, not to the s//.

    $$contents =~ s/$pattern/++$k && $replacement/gex;

    </ajdelore>

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Re: commenting regular expressions?
by tcf22 (Priest) on Sep 04, 2003 at 17:59 UTC
    use the x modifier

    Update: Added example code 
    my $pattern = qr/
    \s*
        <PgfTag `Normal \(T\)'>
    \s*
/x;

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