[CodeGuru]C++ Design Pattern: What is a Design Pattern?

February 9th, 2005, 11:07 AM

Q: What is a Design Pattern?

A: Design Patterns represent solutions to problems what arise when developing software within a particular context.

Quote:

Each pattern describes a problem which occurs over and over again in our environment, and then describes the core of the solution to that problem, in such a way that you can use this solution a million times over, without ever doing it the same way twice.
C. Alexander, The Timeless Way of Building, 1979

Quote:

Patterns help you learn from other's successes, instead of your own failures.
Mark Johnson (cited by Bruce Eckel)

Q: How many types of design patterns exist?

A: Basically, there are three categories:

Creational Patterns: deal with initializing and configuring classes and objects
Structural Patterns: deal with decoupling the interface and implementation of classes and objects
Behavioral Patterns: deal with dynamic interactions among societies of classes and objects

Q: What are good books about design patterns.

A: Here are some must-have books:

Design Patterns by Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides (also known as Gang of Four)
Thinking in Patterns with Java, by Bruce Eckel
Thinking in Patterns with C++, by Bruce Eckel

Q: How can I quickly find information about a design pattern?

A: Here are some links on the web:

General

Design Patterns

Creational Patterns

Abstract Factory: Creates an instance of several families of classes
- resource 1
- resource 2
Builder: Separates object construction from its representation
- resource 1
- resource 2
Factory Method: Creates an instance of several derived classes
Prototype: A fully initialized instance to be copied or cloned
- resource 1
- resource 2
Singleton: A class of which only a single instance can exist
- resource 1
- resource 2

Structural Patterns

Adapter: Match interfaces of different classes
Bridge: Separates an object’s interface from its implementation
- resource 1
- resource 2
Composite: A tree structure of simple and composite objects
Decorator: Add responsibilities to objects dynamically
Façade: A single class that represents an entire subsystem
- resource 1
- resource 2
Flyweight: A fine-grained instance used for efficient sharing
Proxy: An object representing another object
- resource 1
- resource 2

Behavioral Patterns

Chain of Responsibility: A way of passing a request between a chain of objects
- resource 1
- resource 2
Command: Encapsulate a command request as an object
Interpreter: A way to include language elements in a program
- resource 1
- resource 2
Iterator: Sequentially access the elements of a collection
- resource 1
- resource 2
Mediator: Defines simplified communication between classes
- resource 1
- resource 2
Memento: Capture and restore an object's internal state
- resource 1
Observer: A way of notifying change to a number of classes
State: Alter an object's behavior when its state changes
Strategy: Encapsulates an algorithm inside a class
Template Method: Defer the exact steps of an algorithm to a subclass
Visitor: Defines a new operation to a class without change

adiian · #2 February 11th, 2007, 11:38 AM

and more resources on (www.oodesign.com). Make sure you read the design principles, it's very usefull for understanding the desing patterns:

OO Design Principles:
Open Close Principle
Dependency Inversion Principle
Interface Sergregation Principle
Single Responsibility Principle
Liskov's Substitution Principle

Creational Patterns:
Singleton
Factory
Factory Method
Abstract Factory
Builder
Prototype
Object Pool

Behavioral Patterns:
Chain of Responsibility
Command
Interpreter
Iterator
Strategy
Template Method
Visitor