During a hot cb discussion of Scalar::Util::refaddr, I noticed that the pure perl version of the function will alter an unblessed reference passed to it. The sub goes as follows: 

sub refaddr($) {
  my $pkg = ref($_[0]) or return undef;
  bless $_[0], 'Scalar::Util::Fake';
  "$_[0]" =~ /0x(\w+)/;
  my $i = do { local $^W; hex $1 };
  bless $_[0], $pkg;
  $i;
}

[download]
The reblessing to a fake namespace is to eliminate problems from overloading in the target's class, the issue that first made me look at the source.

The oddity is that an unblessed reference will wind up blessed if it is the argument of refaddr. Here's a demo: 

use DynaLoader;                # disable XS loading
sub DynaLoader::bootstrap {1}  # thanks, demerphq

use Scalar::Util qw(refaddr);
my $foo = {};
print $foo, $/;
refaddr $foo;
print $foo, $/;

__END__
HASH(0x804b3f8)
HASH=HASH(0x804b3f8)

[download]
The normally-loaded XS version of the function does not exhibit that behavior.

Pure perl refaddr can be fixed to act like the XS version by making the bless lines conditional on a stored value of Scalar::Util::blessed($_[0]).

My question: Is it worth fixing? Are there any odd side effects of that blessing? Are any significant properties changed?

After Compline,
Zaxo

In reply to A Scalar::Util::refaddr Oddity by Zaxo

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