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

sub test {
   tie $_[0], 'ModName';
}

my $var;
print(tied($var) ? 'tied' : 'not tied', "\n");  # not tied
test($var);
print(tied($var) ? 'tied' : 'not tied', "\n");  # tied