Re: [perl #119793] /x on \Q#foo\E doesn't match '#foo', # becomes special

On Wed, Sep 18, 2013 at 10:56 AM, Nicholas Clark <nick@ccl4.org> wrote:

> Nice bug. I'm not sure if the behaviour is as simple as # being a "dead"
> character or not. If differs depending on whether \E is present:
>
> $ perl -e 'warn "a# " =~ /\Qa# \E/ ? "M" : "."'
> M at -e line 1.
> $ perl -e 'warn "a# " =~ /\Qa# / ? "M" : "."'
> M at -e line 1.
> $ perl -e 'warn "a# " =~ /\Qa# \E/x ? "M" : "."'
> . at -e line 1.
> $ perl -e 'warn "a# " =~ /\Qa# /x ? "M" : "."'
> M at -e line 1.
>

Nice indeed. Easy to see with qr//

$re = qr/\Q#abc\E/x;  print "$re\n";  print '#abc' =~ /$re/ || 0, "\n";
$re = qr/\Q#abc/x;    print "$re\n";  print '#abc' =~ /$re/ || 0, "\n";
$re = qr/\Qabc\E/x;   print "$re\n";  print 'abc'  =~ /$re/ || 0, "\n";

(?^x:\#abc\\E)
0
(?^x:\#abc)
1
(?^x:abc)
1

• [perl #119793] /x on \Q#foo\E doesn't match '#foo', # becomes special by bulk88
• Re: [perl #119793] /x on \Q#foo\E doesn't match '#foo', # becomesspecial by Nicholas Clark
• Re: [perl #119793] /x on \Q#foo\E doesn't match '#foo', # becomes special by Eric Brine