12 February 2014

Designing Pattern

Designing Pattern

  1. Creational Patterns
  2. Strucutural Patterns
  3. Behavioral Patterns

1. Creational Patterns:
Abtaract Factory:
 Provide an interface for creating families of related or dependent objects without specifying their concrete classes.
Builder Patterns:
 Separate the construction of a complex object from its representation so that the same construction process can create different representations.
Factory Method:
 Define an interface for creating an object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.
Prototype Patterns:
 Specify the kind of objects to create using a prototypical instance, and create new objects by copying this prototype.
Singleton Patterns:
   Ensure a class has only one instance and provide a global point of access to it.
2. Strucutural Patterns
Adapter :
  Convert the interface of a class into another interface clients expect. Adapter lets classes work together that couldn't otherwise because of incompatible interfaces.
Bridge :
   Decouple an abstraction from its implementation so that the two can vary independently.
Composite:
 Compose objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.
Decorate:
   Attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
facade:
  Provide a unified interface to a set of interfaces in a subsystem. Fa├žade defines a higher-level interface that makes the subsystem easier to use.
Flyweight:
  Use sharing to support large numbers of fine-grained objects efficiently.
Proxy:
 Provide a surrogate or placeholder for another object to control access to it.
3.Behavioral Patterns
Chain of Responibility:
 Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it.
Command:
 Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations.
Interpreter:
  Given a language, define a representation for its grammar along with an interpreter that uses the representation to interpret sentences in the language.
Iterator:
     Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation.
Mediator:
 Define an object that encapsulates how a set of objects interact. Mediator promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independent.
Memento:
 Without violating encapsulation, capture and externalize an object's internal state so that the object can be restored to this state later.
Observe:
    Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
State:
 Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.
Strategy:
 Define a family of algorithms, encapsulate each one, and make them interchangeable. Strategy lets the algorithm vary independently from clients that use it.
Template Method:
 Define the skeleton of an algorithm in an operation, deferring some steps to subclasses. Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.
Visitor:
  Represent an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates.

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