An object is [[polymorphism|polymorphic]] when its specific type may vary.
The types a specific value may take, is called ''class''.

It is trivial to copy an object if its type is known:
<lang c>int x;
int y = x;</lang>
Here x is not polymorphic, so y is declared of same type (''int'') as x.
But if the specific type of x were unknown, then y could not be declared of any specific type.

The task: let a polymorphic object contain an instance of some specific type S derived from a type T.
The type T is known.
The type S is possibly unknown until [[run time]].
The objective is to create an exact copy of such polymorphic object (not to create a [[reference]], nor a pointer to).
Let further the type T have a method overridden by S.
This method is to be called on the copy to demonstrate that the specific type of the copy is indeed S.