Design patterns in .net

What are Design Patterns?

To say what design patterns are in a single sentence is difficult but we can say as design patterns are :

• Solutions to recurring design problems.

• They are a set of rule which help the developer to accomplish a certain task.

• Design patterns are architectural patterns and generalized solutions , which can be applied when needed.

• These are standardized and efficient solutions to software design and programming problems that are re-usable.

Generally Gang-of-Four(GoF) are used.

Why to Use Design Patterns?

Design patterns are proven solution templates, using design templates not only reduces the overhead of architecting a solution afresh but these are also  optimized ,easy to do , easy to learn solutions.

What are the common design patterns used?

CREATIONAL	creational design patterns are design patterns that deal with object creation mechanisms, trying to create objects in a manner suitable to the situation
STRUCTURAL	Design Patterns that ease the design by identifying a simple way to realize relationships between entities.
BEHAVIOURIAL	Identify common communication patterns between objects and realize these patterns.

CREATIONAL PATTERNS

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

STRUCTURAL PATTERNS

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

BEHAVIORIAL

Chain of Resp.	A way of passing a request between a chain of objects
Command	Encapsulate a command request as an object
Interpreter	A way to include language elements in a program
Iterator	Sequentially access the elements of a collection
Mediator	Defines simplified communication between classes
Memento	Capture and restore an object's internal state
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

Patterns I have used?

I have used Creational and Structural and have never implemented any Behaviorial Pattern.

In Creational I have used:

• Abstract Factory
• Factory Method
• Singleton Method

In Structural I have used

• Adapter Pattern
• Facade Pattern

Other patterns I know are:

• Decorator
• Builder
• Iterator

Can we create our own pattern?

Whenever a certain solution that is reusable in a vast majority of your projects, it can be abstracted to a design pattern and cab be used across the organisation.