Calling the overridden method from the base class in C#

Question

Given the following C# class definitions and code:

public class BaseClass
{
    public virtual void MyMethod()
    {
        ...do something...
    }
}

public class A : BaseClass
{
    public override void MyMethod()
    {
        ...do something different...
    }
}

public class B : BaseClass
{
    public override void MyMethod()
    {
        ...do something different...
    }
}

public class AnotherObject
{
    public AnotherObject(BaseClass someObject)
    {
        someObject.MyMethod(); //This calls the BaseClass method, unfortunately.
    }
}

I would like to call the MyMethod() that is actually found in A or B, assuming the object passed in is actually an instance of A or B, not that which is found in BaseClass. Short of doing something like this:

public class AnotherObject
{
    public AnotherObject(BaseClass someObject)
    {
        A temp1 = someObject as A;
        if (A != null)
        {
            A.MyMethod();
        }
        
        B temp2 = someObject as B;
        if (B != null)
        {
            B.MyMethod();
        }
    }
}

How can I do it?

Answer 1

Which method is called is determined via polymorphism on the type that is passed into the AnotherObject constructor:

AnotherObject a = new AnotherObject(new A()); // invokes A.MyMethod() 
AnotherObject b = new AnotherObject(new B()); // invokes B.MyMethod() 
AnotherObject c = new AnotherObject(new BaseClass()); //invokes BaseClass.MyMethod()