use strict ;

sub calc_add_long {
	return calc->add_long(@_) ;
}


*{calc_add_double} = \&calc_add_long ;
*{calc_add_string} = \&calc_add_long ;



package calc ;

sub new {
	my $class = shift ;

	my $this = {} ;
	bless($this, $class) ;

	return $this ;
}


sub add_long {
	my ($this, $a, $b) = @_ ;

	if ((! defined($a))||(! defined($b))){
		return undef ;
	}

	return $a + $b ;
}


*{calc::add_double} = \&calc::add_long ;
*{calc::add_string} = \&calc::add_long ;


1 ;