#O reilly programming php software
#O reilly programming php code

Represent the behavior of things and not the thing. If you can add more behaviors without modifying any of the existing behavior classes or touching any of the superclasses we've achieved a good strategy design pattern. Use an interface to represent each behavior and Each implementation of a behavior will implement one of those interface. Program to an interface not an implementationĪn interface in this context could also refers to an abstract class or class that implements particular behavior When you have subclasses that differ in a behavior(s) pull out what varies and (encapsulate) create new set of classes to represent each behavior.

Take the parts that vary and encapsulate them, so that later you can alter or > extend the parts that vary without affecting those that don’t.Įncapsulate what change and you will have flexible system. Identify the aspects of your application that vary and separate them from what stays the same.Īnother way to think about this principle:

#O reilly programming php code

The Example in the book shows that when inheritance hasn’t worked out very well, since the behavior keeps changing across the subclasses and it's not appropriate for all subclasses to have those behaviors, The interface solution sounds promising and can be done in PHP using Traits but cant be done in java because java have no code reuse so in java if there's a change you have to track down all the subclasses where that behavior is defined probably introducing new bugs along the way!

#O reilly programming php software

NotesĬHANGE is the one constant in software development. Strategy pattern is used when we have multiple algorithms for specific task and the client decides the actual implementation to be used at runtime. Strategy lets the algorithm vary independently fromĬlients that use it. The Strategy Pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable. Chapter 3 : Decorator Pattern (Design Eye for The Inheritance Guy)Ĭhapter 4 : Factory method, Abstract factory, Dependency InversionĬhapter 7 : The Adapter and The Facade PatternsĬhapter 8 : Template Method Pattern Ĭhapter 9 : The Iterator and Composite Patterns Well-Managed CollectionĬhapter 10 : The State Pattern The State of ThingsĬhapter 11 : The Proxy Pattern Controlling Object Accessĭefines a set of encapsulated algorithms that can be swapped to carry out a specific behavior.