Automatically call base method

Question

I need to call automatically base class method when calling overriden one (like constructors call base). For example:

class A
{
    public void Fun()
    {
        Console.Write("Class A!");
    }
}

class B : A
{
    public void Fun()
    {
        Console.Write("Class B!");
    }
}

I want to see on the screen

Class A! Class B!

when executing next code:

B b = new B();
b.Fun();

Could anyone tell me please what need to change in example code or how better to write to get required result? Thanks.

Answer 1

If you don't want to call it explicitly and therefore ensure A.Fun() is called in the derived class, you could use something called the template method pattern:

class A
{
    public void Fun()
    {
        Console.Write("Class A!");
        FunProtected();
    }

    protected virtual void FunProtected()
    {
    }
}

class B : A
{
    protected override void FunProtected()
    {
        Console.Write("Class B!");
    }
}

This would give you:

new A().Fun() -> "Class A!"
new B().Fun() -> "Class A! Class B!"