Hands-On Design Patterns with C++

Polymorphic copy

So far, we have considered factory alternatives to the object constructor—either the default constructor or one of the constructors with arguments. However, a similar pattern can be applied to the copy constructor—we have an object, and we want to make a copy.

This is a similar problem in many ways—we have an object that's accessed through the base class pointer, and we want to call its copy constructor. For the reasons we discussed earlier, not the least of which is that the compiler needs to know how much memory to allocate, the actual constructor call has to be done on the statically determined type. However, the control flow that gets us to a particular constructor call can be determined at runtime, and that, again, ...