Design Patterns: Adapter (Wrapper)

Posted by Monik, 27 October 2010.
Programming Code Design Design Patterns
Book summary
Summary on basis of the book ,,Design Patterns: Elements of Reusable Object-Oriented Software'', by Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides, Addison-Wesley, 1995.

We have incompatible interfaces and we want to convert one interface to match the other.

The thing we want to adapt we either:
  • compose in a class that implements the required interface (object adapter)
  • extend by a class that implements the required interface (class adapter)
the class that implements the required interface is called adapter.

* adapter can add new functionality which adaptee does not provide

Class adapter vs Object adapter:
  • class adapter will not automatically work for subclasses of adaptee :(
  • class adapter allows easily to override adaptee's methods :)
  • object adapter can easily adapt several adaptees :)

* pluggable adapters

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