Design Patterns

Object Oriented Design Principles

Program to an interface, not an implementation.

Favor object composition over class inheritance.

This post is like a reference to all GoF design patterns introduced in This Developer's Planet blog.

Creational Patterns
		Factory Method Creates an instance of several derived classes
		Abstract Factory Creates an instance of several families of classes
		Singleton  A class of which only a single instance can exist
		Prototype  A fully initialized instance to be copied or cloned
		Builder Separates object construction from its representation
Structural Patterns
		Façade  A single class that represents an entire subsystem
		Proxy  An object representing another object
		Adapter  Match interfaces of different classes
		Composite  A tree structure of simple and composite objects
		Bridge  Separates an object’s interface from its implementation
		Decorator  Add responsibilities to objects dynamically
		Flyweight  A fine-grained instance used for efficient sharing
Behavioral Patterns
	Iterator  Sequentially access the elements of a collection
	Observer  A way of notifying change to a number of classes
	Command  Encapsulate a command request as an object
	Strategy  Encapsulates an algorithm inside a class
	Template Method  Defer the exact steps of an algorithm to a subclass
	State  Alter an object's behavior when its state changes
	Chain of Resp.  A way of passing a request between a chain of objects
	Mediator  Defines simplified communication between classes
	Visitor  Defines a new operation to a class without change
	Memento  Capture and restore an object's internal state
	Interpreter  A way to include language elements in a program
Other Patterns
	Pipeline  A way of passing a request between a chain of objects
	Object Pool Sharing and reusing the expensive resources
	Null Object A Null Object is an object with defined neutral behaviour