Design Patterns

We have taken the exam all our lives and seen that there are solution methods for every question type. Methods that go to solution easily accepted as solving techniques. Like this, solving techniques were developed for problems where occur in computer science also. They were called design patterns.

Erich Gamma, Richard Helm, Ralph Johnson ve John Vlissides Design Patterns are known as the Gang of Four (GOF) mentioned about Design Patterns at Elements of Reusable Object-Oriented Software book, after this Design patterns gained popularity.

Design patterns grouped into three titles.

1- Creational Patterns: Creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation. Example: Singleton, Factory, Abstract Factory, Builder, Prototype.

2- Structural Patterns: Structural design patterns ease the design by identifying a simple way to realize relationships among entities. Example: Adapter, Bridge, Composite, Decorator, Facade, Flyweight, Proxy.

3- Behavioral Patterns: Behavioral design patterns are concerned with algorithms and the assignment of responsibilities between objects. Example: Chain of Responsibility, Command, Interpreter, Iterator, Mediator, Memento, Observer, Null Object, Strategy, State, Visitor.

There are different amount design patterns in different sources.

Anti Patterns

An anti-pattern is a common response to a recurring problem that is usually ineffective and risks being highly counterproductive. The term, coined in 1995 by computer programmer Andrew Koenig, was inspired by the book Design Patterns, which highlights a number of design patterns in software development that its authors considered to be highly reliable and effective. (Wikipedia)