$\ = $/;
$h = '';
${''}{foo} = 'bar';
print "\$h->{foo}: ", $h->{foo};
print "\$h: '", $h, "'";

print *{''}{HASH};
print *{$h}{HASH};

$h = undef;
print *{$h}{HASH};
__END__
$h->{foo}: bar
$h: ''
HASH(0x885d7a4)
HASH(0x885d7a4)
Can't use an undefined value as a symbol reference at - line 11.