// Contravariance in Java 1.8

class person implements Comparable<person>
{
    public String name;
    public int compareTo(person x) {return name.compareTo(x.name);}
}

class student extends person implements Comparable<person>
{
    public double gpa;
    //    public int compareTo(person x) {return name.compareTo(x.name);}    
    // can the compareTo method be inherited?
}

//class C<T extends Comparable<T>> // usual form
class C<T extends Comparable<? super T>> // new jdk 1.8 form
{

    static void notreallymain()
    {
	C<student> y = new C<student>(); // won't compile without "super"
	//	C<person> z = new C<student>();  // but can't be covariant
    }   
}


// what if I try to do a super on a return type?  -- following won't compile
/*
interface D<T>
{
   T f();
}
class DD implements D<person>
{
    public person f() { return null; }
}
class CC<T extends D<? super T>>
{
    static void stillnotmain()
    {
	CC<student> x = new CC<student>();
    }
}
*/