Overloading……A Matter Of Taste !!!

This was a pretty interesting discussion about method overloading in the managed world. As the discussion says that the overloading is a matter of taste. It seems that the method overloading in the managed world, indeed, is a matter of taste. Sad BUT True !!! But on the contrary, it must have been a [strict] rule. Overloading might be exhibited differently by each language in the unmanaged world. But as far as .NET goes, it must have been made a standard specification. Pardon me, if there is one.

As it was pointed out in the discussion, how do we define the behaviour in the case where we derive classes across assemblies developed in another .NET language ?

As far traditional C++ goes, the overloaded method resolution starts from the derived but does not have strict type checking eg. for numeric types]. And the point to note is that only the method in the derived class with the exact prototype as the base is considered the overload. Ofcourse, C++ is not as much type safe as C#. This is taken care in C# by the override keyword which allows only the exact prototypes to be involved in overloading. And at times explicit casting is required unlike in C++.

But in the case of C#, the first principle observed in overloading is to avoid it. Pretty confusing, huh? Take a look at the example below:-

namespace Samples.MyConsole
{
   class Parent
   {
       public void Foo()
       {
           Console.WriteLine("Parent.Foo");
       }
   }

   class Child : Parent
   {
       public void Bar()
       {
           Console.WriteLine("Child.Bar");
       }
   }

   class Base
   {
       public virtual void XYZ(Child c)
       {
           c.Foo();
           c.Bar();
       }
   }

   class Derived : Base
   {
       public virtual void XYZ(Parent p)
       {
           p.Foo();
       }

       public override void XYZ(Child c)
       {
           base.XYZ(c);
       }
   }

   class User
   {
       public static void SomeMethod()
       {
           Child c = new Child();
           Parent p = c as Parent;

           Derived d = new Derived();
           Base b = d as Base;

           Console.WriteLine("Playing with Derived");
           d.XYZ(c);
           d.XYZ(p);

           Console.WriteLine("\nPlaying with Base");
           b.XYZ(c);
           b.XYZ(p as Child);
       }
   }
}

Here is the output at the console:-

Playing with Derived
Parent.Foo
Parent.Foo

Playing with Base
Parent.Foo
Child.Bar
Parent.Foo
Child.Bar

You would have guessed the surprise that you are about to experience. Yes, d.XYZ(c) calls the Derived.XYZ(Parent p), and not the Derived.XYZ(Child c) which is a better match. It does if it had been defined as public new void XYZ(Child c). But same is not the case with C++. It gives us no suprise.

And as far as C++/CLI is concerned, it behaves as traditional C++.

So the intriguing bitter part is that the overloading in the managed world is not a thing at the CLR level nor does it seem to be something concerned with the specification. It seems to be a matter of taste.