A Quick Pattern Summary

Pattern name	Solves what problem?
Delegation	Defers implementatian af a methad ta a data member
Template method	Defers implementation of part of a method to a subclass
Iterator	Encapsulates traversal of a collection
Singleton	Ensures that on I y a single instance of a class exists
Proxy	Provides an extra level of indirection in an interface
Façade	Provides a single interface object to many implementation objects
Adapter	Converts one interface object to a different implementation object
Bridge	Decouples an interface object from its implementation object
Composite	Interfaces to objects that may be simple or nested composites
Observer	Keeps objects and dependent views consistent
Mediator	Provides an interface object to mediate interaction
Command	Encapsulates a request as an object
Chain of responsibility	Decouples senders from request receivers
Visitor	Applies various algorithms to object hierarchies
Prototype	Clones objects
Builder	Builds composite objects with different representations
Factory method	Defers instantiation to subclasses
Abstract factory	Creates families of objects of varying subclasses
Memento	Saves and restores an object's state
Flyweight	Allows many objects to share state efficiently
Strategy	Encapsulates an operation as an object
Interpreter	Inputs analysis and language processing
State	Allows objects to appear to change their state
Decorator	Adds properties and operations to objects dynamically

Gang of Four (Gof) pattern classification

		Purpose
		Creational	Structural	Behavioural
Scope	Class (static)	Factory Method	Adapter (class)	Interpreter
	Class (static)	Factory Method	Adapter (class)	Template Method
	Object (dynamic)	Abstract Factory	Adapter (object)	Chain of Respnsability
		Builder	Bridge	Command
		Prototype	Composite	Iterator
		Singleton	Decorator	Mediator
			Façade	Memento
				Observer
				State
				Strategy
				Visitor

Application-based pattern classification

General	Interface	Views and Controllers	Database and persistence	Table-driven Control	Roles
Delegation	Proxy	Observer	Prototype	Interpreter	State
Template Method	Façade	Mediator	Builder	Strategy	Decorator
Iterator	Adapter	Command	Factory Method
Singleton	Bridge	Chain of Reponsability	Abstract Factory
	Composite	Visitor	Memento
			Flyweight