Casting child to parent with generics

Question

Class a <T> {
   public T j;
}

class b:a <int> {

}

If this were not a generic then you could do the following:

a foo = new b();

Is there anyway to do the same with the generic case?

Is there a better method to do that?

Answer 1

您可以使用：

a<int> foo = new b();

Answer 2

You need the generic parameters declared in a :

class a<T>
{
    public T j;
}

You also need them in b to be able to derive from a :

class b<T> : a<T> { }

and then you can cast b<T> to a<T> :

a<int> foo = new b<int>();

Or you can derive from specific a :

class b : a<int> { }

and then cast:

a<int> foo = new b();

Answer 3

public static void Main()
{
    Base<int> foo = new Derived();
}

class Base<T>
{
    public T data;
}

class Derived:Base<int>
{
}