Chapter 16, Adapters and Decorators

1. The Adapter is a very general pattern that modifies an interface of a class or a function (or a template, in C++) so it can be used in a context that requires a different interface but similar underlying behavior.
2. The Decorator pattern is a more narrow pattern; it modifies the existing interface by adding or removing behavior but does not convert an interface into a completely different one.
3. In the classic OOP implementation, both the decorated class and the Decorator class inherit from a common base class. This has two limitations; the most important one is that the decorated object preserves the polymorphic behavior of the decorated class but cannot preserve the interface that is added in a concrete (derived) decorated class and was not present in the base class. The second limitation is that the Decorator is specific to a particular hierarchy. We can remove both limitations using the generic programming tools of C++.
4. In general...