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// Only derived types can support this

// "polymorphic interface." Classes in other

// heirarchies have no access to this abstract

// member.

public abstract object Clone();

}

Given this definition, only members that extend CloneableType are able to support the Clone()

method. If you create a new collection of classes that do not extend this base class, you are unable

to gain this polymorphic interface. As you would guess, interface types come to the rescue. Once an

interface has been defined, it can be implemented by any type, in any hierarchy, within any name-

spaces or any assembly (written in any .NET programming language). Given this, interfaces are

highly polymorphic. Consider the standard .NET interface named ICloneable defined in the System

namespace. This interface defines a single method named Clone():

public interface ICloneable

{

object Clone();

}

If you were to examine the .NET Framework 3.5 SDK documentation, you would find that a

large number of seemingly unrelated types (System.Array, System.Data.SqlClient.SqlConnection,

System.OperatingSystem, System.String, etc.) all implement this interface. Although these types

have no common parent (other than System.Object), we can treat them polymorphically via the

ICloneable interface type.

For example, if we had a method named CloneMe() that took an ICloneable interface parame-

ter, we could pass this method any object that implements said interface. Consider the following

simple Program class defined within a Console Application named ICloneableExample:

class Program

{

static void Main(string[] args)

{

Console.WriteLine("***** A First Look at Interfaces *****\n");