I liked this enough that I bookmarked this in my delicious collection -- helped me debug a nasty problem.

I did things slightly differently though -- more localized, I think.

    {
      local $SIG{__WARN__} = sub {
        my @warnings = @_;
        foreach my $warning (@warnings) {
            print "got a warning: $warning\n";
          }
      };
      eval {'' =~ /$re/ };
    }
[download]

cheers.