GOF Design Patterns C#

A design pattern is a reusable solution to a recurring problem in software design.

Benefits of using Design Patterns

  • Best Practices – Design patterns represent the best practices used by experienced software developers.
  • Language Independent – Design Patterns are language neutral and so can be applied to any language that supports object-orientation.
  • Reusable : Design Patterns provides solutions that can be reused to solve similar kind of problem.
  • Flexible: Design Patterns provides structure to solve a generalized problem which can be modified to suit the specific need.

GOF Design Pattern Catogeries

There are 23 Gang of Four (GoF) design patterns, that are generally considered the foundation for all other patterns. These are categorized under three groups:

  • Creational
  • Structural
  • Behavioral

1. Creational Design Patterns

These design patterns provide a way to create objects while hiding the creation logic, rather than instantiating objects directly using new operator. This helps in deciding which objects need to be created for a given use case.

  Abstract FactoryCreates an instance of several families of classes
  BuilderSeparates object construction from its representation
  Factory MethodCreates an instance of several derived classes
  PrototypeA fully initialized instance to be copied or cloned
  SingletonA class of which only a single instance can exist

2. Structural Design Pattern

These design patterns concern class and object composition to form a larger structure. Inheritance is used to compose interfaces and define ways to compose objects to add new functionalities.

 AdapterMatch interfaces of different classes
  BridgeSeparates an object’s interface from its implementation
  CompositeA tree structure of simple and composite objects
  DecoratorAdd responsibilities to objects dynamically
  FacadeA single class that represents an entire subsystem
  FlyweightA fine-grained instance used for efficient sharing
  ProxyAn object representing another object

3. Behavioral Design Patterns

These design patterns are specifically concerned with communication between objects.
  Chain of Resp.A way of passing a request between a chain of objects
  CommandEncapsulate a command request as an object
  InterpreterA way to include language elements in a program
  IteratorSequentially access the elements of a collection
  MediatorDefines simplified communication between classes
  MementoCapture and restore an object’s internal state
  ObserverA way of notifying change to a number of classes
  StateAlter an object’s behavior when its state changes
  StrategyEncapsulates an algorithm inside a class
  Template MethodDefer the exact steps of an algorithm to a subclass
  VisitorDefines a new operation to a class without change