What is a two-way adapter pattern

Question

In the book Design Patterns by GoF (Eric Gamma and others), two-way adapter pattern is mentioned which is used for transparency. They are useful when 2 different clients want to view the same object differently. Could some one give a C++ example for the same and in which practical scenarios it can be used ??

Answer 1

The Two-Ways Adapters are adapters that implements both interfaces of Target and Adaptee. The adapted object can be used as Target in new systems dealing with Target classes or as Adaptee in other systems dealing with Adaptee classes. Going further on this line of thinking, we can have adapters implementing n interfaces, adapting to n systems. Two-way adapters and n-way adapters are hard to implement in systems not supporting multiple inheritance. If adapter has to extend the Target class it can not extent another class like Adaptee, so the Adaptee should be an interface and all the calls should be delegated from the adapter to the Adaptee object.

Source: http://www.oodesign.com/adapter-pattern.html

Answer 2

I find that the explanation given here is quite good. It is a C# example but the explanation is clear and the example can quite easily be translated into C++ code. The example is also quite detailed.