sub ModName::TIESCALAR {
   my $class = shift;
   my $self;
   return bless(\$self, $class);
}

sub ModName::FETCH { }

tie my $src, 'ModName';
print(tied($src) ? 'tied' : 'not tied', "\n");  # tied

my $dst = $src;
print(tied($dst) ? 'tied' : 'not tied', "\n");  # not tied