C-Sharp (C#) Group: Up casting (base to derived) in C#

Hey All,

I have a C# question for you regarding up casting (base to
derived).

I was wondering about the most elegant way (readable, less
code)  to
cast from a base type to its derived type. Please consider
the
following two classes:

    class Base {
        private int m_valA;
        private int m_valB;

        public Base() { }

        public Base(int a, int b){
            m_valA = a;
            m_valB = b;
        }

        public int ValA
        {
            get { return m_valA; }
            set { m_valA = value; }
        }

        public int ValB
        {
            get { return m_valB; }
            set { m_valB = value; }
        }
    }//end class

    class Derived : Base
    {
        public int ValAPlusValB
        {
            get { return base.ValA + base.ValB; }
        }
    }//end class

Now consider the scenario where I have an instance of Base
(someBase)
and could like to up cast it to a Derived instance
(someDerived).


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Pete,
     I would have responded sooner, but I've been hoping
that someone
else would, to be perfectly honest. I would have to say that
my biggest
question in this entire scenario is this: I cannot fathom
the latter
scenario you have mentioned.

When will a base class ever need to be cast into a phantom
child class?
You would only need to cast when the child needs to be
compared to what
'else' it is. If you stop on a lower level, then the base
is never
anything 'else'.

I mean no disrespect in this, as I'm sure I have just
missed something
overly obvious and will be smacking myself for it later, but
the best
way I can sum this up is to say that a cub came from a bear,
but never
has a cub turned around and created a bear in return.

Please elaborate your position if I somehow went brain-dead
(as I often
do) and missed it. Thanks much in advance.


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