Question

I have the following set up:

public abstract class A
{
    public void f()
    {
        //Want to make an instance of B or C here
        //A bOrC = new ?
    }
    public abstract void f2();
}
public class B : A { public override void f2(){} }
public class C : A { public override void f2(){} }

Is this possible? If so how?

Edit: bOrC needs to be the type of the particular derived class f() is called from

Answer 1

I can think of two ways to solve this issue. One uses generics and the other just requires an abstract method. First the simple one.

public abstract class A
{
    public void f()
    {
        A bOrC = newInstance();
    }
    public abstract void f2();
    protected abstract A newInstance();
}
public class B : A {
    public override void f2(){}
    public override A newInstance(){
        return new B();
    }
}
public class C : A {
    public override void f2(){}
    public override A newInstance(){
        return new C();
    }
}

And now with generics

public abstract class A<T> where T : A, new()
{
    public void f()
    {
        A bOrC = new T();
    }
    public abstract void f2();
}
public class B : A<B> {
    public override void f2(){}
}
public class C : A<C> {
    public override void f2(){}
}