Design Patterns GoF

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Design Patterns(GoF)

• Ilker Acar
• MSP
• Ilker.acar_at_msakademik.net

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Agenda

• Overview
• Why Pattern?
• Design Patterns
• Creational Patterns
• Structural Patterns
• Behavioral Patterns
• References

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Overview

• Pattern Best solution for a problem
• 23 GoF Patterns, Gangs Of Fours

• Creational Patterns (5)
• Singleton,Abstract Factory, Factory Method,
  Builder, Prototype
• Structural Patterns (7)
• Adapter,Bridge,Composite,Decorator,Facade,Flyweig
  ht,Proxy
• Behavioral Patterns (11)
• CoR,Command,Interpreter, Iterator,
  Mediator,Memento,Observer, State,Strategy,
  Template Method, Visitor

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Why Pattern?

• Easy to Manage
• Best Practices
• Modification
• Extensibility
• Reusability

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Creational Patterns
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CP- 01 Singleton
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CP- 01 Singleton(contd.)

• Intent
• Ensure a class only has one instance, and provide
  a global point of access to it.
• Examples
• Printer spooler, Window manager, File System,
  LoadBalancer

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CP-O2 Abstract Factory (contd.)

• Intent
• Provide an interface for creating families of
  related or dependent objects without specifying
  their concrete classes.
• Examples
• Database Infrastructure, Windows/Web Forms

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CP-O2 Abstract Factory (contd.)
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CP- 03 Factory

• Intent
• Define an interface for creating an object, but
  let subclasses decide which class to instantiate.
  Factory Method lets a class defer instantiation
  to subclasses.

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CP-04 Builder

• Intent
•  Separates object construction from its
  representation

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CP-05 Prototype

• Intent
• A fully initialized instance to be copied or
  cloned

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Structural Patterns
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SP-01 Adapter

• Intent
• Convert the interface of a class into another
  interface clients expect. Adapter lets classes
  work together that couldn't otherwise because of
  incompatible interfaces.

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SP-02 Bridge

• Intent
• Separates an objects interface from its
  implementation

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SP-03 Composite

• Intent
• A tree structure of simple and composite objects

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SP-04 Decorator

• Intent
•  Add responsibilities to objects dynamically

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SP-05 Facade

• Intent
• A single class that represents an entire
  subsystem

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SP-06 Flyweight

• Intent
• Use sharing to support large numbers of
  fine-grained objects efficiently.

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SP-07 Proxy

• Intent
• An object representing another object

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Behavioral Patterns
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BP-01 Chain of Responsibility

• Intent
• A way of passing a request between a chain of
  objects

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BP-02 Command

• Intent
• Encapsulate a command request as an object
• Examples
• Undo/ Redo Operations

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BP-03 Interpreter

• Intent
• Given a language, define a representation for its
  grammar along with an interpreter that uses the
  representation to interpret sentences in the
  language.

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BP-04 Iterator

• Intent
• Sequentially access the elements of a collection

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BP-05 Mediator

• Intent
•  Defines simplified communication between classes

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BP-06 Memento

• Intent
•  Capture and restore an object's internal state

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BP-07 Observer

• Intent
• A way of notifying change to a number of classes

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BP-08 State

• Intent
•  Alter an object's behavior when its state
  changes

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BP-09 Strategy

• Intent
•  Encapsulates an algorithm inside a class

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BP-10 Template Method

• Intent
• Defer the exact steps of an algorithm to a
  subclass

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BP-11 Visitor

• Intent
• Defines a new operation to a class without change

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BP-11 Visitor (contd.)
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Summary

• 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

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Summary (contd.)

• Structural Patterns
• Adapter    Match interfaces of different
  classes   
• Bridge    Separates an objects 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

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Summary (contd.)

• Behavioral Patterns
• 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 M. Defer the exact steps of an
  algorithm to a subclass  
•  Visitor    Defines a new operation to
  a class without change

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References / Useful Sources
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Questions

• ?

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Thank You !

• Ilker Acar
• Microsoft Student Partner (MSP)
• Contact
• Mail ilker.acar_at_msakademik.net
• Web http//www.ilkeracar.com
• Blog http//iacar.spaces.live.com