Question

Ok lets say I have two classes with the same method(sampleMethod) which is overridden by the child: ObjectParent and ObjectChild

ObjectChild ExampleVariable = new ObjectChild();
(ExampleVariable as ObjectParent).sampleMethod();

Will this call the sampleMethod from ObjectChild or from ObjectParent??

I think it will call the sampleMethod from ObjectChild, but I want to make sure before I throw down a bunch of code based on that assumption.

Answer 1

Will this call the sampleMethod from ObjectChild or from ObjectParent?

Assuming it’s really a virtual method which is properly overridden (rather than just being hidden), it will call the ObjectChild implementation. That’s the whole point of virtual methods – that you don’t need to know the execution-time type at compile-time. For example, I can write a method using Stream.Read (e.g. by taking the Stream as a parameter) without knowing which implementation of Stream it will end up using. At execution time that code could end up reading from the network, from memory, from disk… my method’s code neither knows nor case.

Short but complete program demonstrating this:

using System;

class ObjectParent
{
    public virtual void Foo()
    {
        Console.WriteLine("ObjectParent.Foo");
    }
}

class ObjectChild : ObjectParent
{
    public override void Foo()
    {
        Console.WriteLine("ObjectChild.Foo");
    }
}

class Test
{
    static void Main()
    {
        // Simpler code to demonstrate the point
        ObjectParent parent = new ObjectChild();
        parent.Foo(); // Prints ObjectChild.Foo
    }
}