I'd use this more often, but it kind of feels strange. Like wearing shoes that are too big, perhaps. You're looping one thing, which means that this is an un-loop. In fact, it's really just a fancy way of making a reference:

for my $foo ($_[0]->{bar}->{baz})
{
      if ($foo->{gronk})
      {
            $foo = { glarb => "oorgle" };
      }
}
[download]

It's a lot easier than making $$foo reference that thing and then constantly dereferencing it.