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Regex re_eval - requires explicit package name

by trizen (Friar)
on Jan 20, 2013 at 10:36 UTC ( #1014279=perlquestion: print w/ replies, xml ) Need Help??
trizen has asked for the wisdom of the Perl Monks concerning the following question:

Hello dear Monks,

Today I've encountered a problem which, really, drives me crazy.
Here is a small portion of the code which illustrates my issue:
#!/usr/bin/perl use 5.010; use strict; use warnings; use re 'eval'; sub make_esc_delim { my ($delim) = @_; return qr{\Q$delim\E[^$delim\\]*+(?>\\.|[^$delim\\]+)*\Q$delim\E}s +; } my $str_dq = make_esc_delim(q{"}); my %bpairs; { local $" = q{}; foreach my $d ([qw~< >~], [qw~( )~], [qw~{ }~], [qw~[ ]~]) { my @ed = map {quotemeta} @{$d}; $bpairs{$d->[0]} = qr{ $ed[0] (?<content> (?> (??{$bpairs{$d->[0]}}) (?{print "After eval!\n"}) | (?> $str_dq | [^@ed] ) )* ) $ed[1] }xs; } } my $x = q~func{{xx|"}"} @{d}end}~; if($x =~ /$bpairs{'{'}/){ print "First matched: $&\n"; } if($x =~ /func$bpairs{'{'}/){ # here is the problem print "Second matched: $&\n"; }
Output:
After eval! After eval! First matched: {{xx|"}"} @{d}end} Global symbol "$d" requires explicit package name at (re_eval 9) line +1. Compilation failed in regexp at test.pl line 43.

The question is: why perl doesn't let me to add some text around the compiled regex that embeds reevaluation of itself?
Should I consider this a bug?
Is there any other way around this issue?

Currently, I'm using: perl 5, version 16, subversion 2 (v5.16.2) built for i686-linux-thread-multi

Thank you very much.

Comment on Regex re_eval - requires explicit package name
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Re: Regex re_eval - requires explicit package name
by dave_the_m (Parson) on Jan 20, 2013 at 10:43 UTC
    It's a bug. Fixed in 5.17.1.

    Dave.

Re: Regex re_eval - requires explicit package name
by Anonymous Monk on Jan 20, 2013 at 10:50 UTC
      I vaguely recall that with this experimental feature, you're supposed to use dynamic/local vars instead of lexical/my vars
      That's because the code was exceedingly buggy and would usually use the wrong pad, resulting in unexpected behaviour or seg faults before 5.17.1 (for which I completely rewrote the feature). Its now safe and sane to use lexicals, modulo any new bugs I may have introduced.

      Dave.

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