I need to go back from the stringified form of a regexp to a real regexp. The regexp is stringified when I use it as the key to a hash (which I have to do as the current API dictates the use of a hash here).

The little bit of code below explains what happens and what I have done to get the regexp back.

#!/usr/bin/perl -w
use strict;

my $regexp = qr/^x/i;                             # a regexp

# stringify it
my $hash   = { $regexp => 1 };                    # keys are stringifi
+ed
my $string = (keys %$hash)[0];                    # a string

print "$string (ref: ", ref $string,")\n";        # and I prove it!
                                                  # the string is: '(?
+i-xsm:^x)'

# regex-ify it
if( $string=~m{^\(\?([xism]*)-([xism]*):(.*)\)$}) # match the interest
+ing bits    
  { my $nregexp= qr/(?$1:$3)/;                    # rebuild it
    print "$nregexp (ref: ", ref $nregexp,")\n";  # a regexp again! 
                                                  # it stringifies as 
+'(?-xism:(?i:^x))'
  }

[download]

My questions are: did I forget anything? Does it work accross versions of perl (I tested it under 5.8.6)? Is there anything simple that I forgot/did not know about?

In reply to Converting a stringified regexp back into a regexp by mirod

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