Question

I want to define some generic class that

class A : IClonable
{
    clone();
}

I want to define a new class that derivative from class T but base class of T is A ==> so if the new class is B i will be able to call to Clone without define the IClonable in class B again.

How can i do this ?

Answer 1

I think you’re asking how to make the clone method available on MyClass when T inherits from ICloneable. That’s not possible without explicity stating that MyClass also inherits from IClonable since MyClass isn’t inheritting from T; it’s simply a class which has methods / properties which in some way relate to T (i.e. allowing operations to be formed on classes of type T.

The closest I could come up with to allow you to access T through the generic class is to hack the default indexer property; that way by adding [1] to the end of your MyClass instance you’ll be looking at a single instance of a T clone.

    class A : ICloneable
    {
        public object Clone()
        {
            throw new NotImplementedException();
        }
        public override string ToString()
        {
            return "Demo";
        }
    }
    class B<T> where T : A
    {
        T myT;

        public B(T value)
        {
            this.myT = value;
        }

        //hack the default indexer to instead allow it to be used to return N clones of myT
        public IEnumerable<T> this[int index]
        {
            get
            {
                for (int i = 0; i < index; i++)
                {
                    yield return (T)this.myT.Clone();
                }
            }
        }
    }

    class Program
    {
        public static void Main(string[] args)
        {
            B<A> myB = new B<A>(new A());
            Console.WriteLine( myB[1].ToString());
            Console.ReadKey();
        }
    }