Builder A Creational Design Pattern

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BuilderA Creational Design Pattern

• A Presentation by Alex Bluhm
• And

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What are Creational Design Patterns?
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Creational Design Patterns

• Abstract instantiation process
• Flexibility in whats created, who creates it,
  how its created and when
• Patterns
• Abstract Factory
• Builder
• Factory Method
• Prototype
• Singleton

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Builder Design Pattern

• Separates the construction of a complex object
  from its representation
• Same construction process can create different
  representations
• Bob says

Builders specify abstract interfaces for creating
parts of a Product object
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Participants in Builder Pattern

• Builder
• ConcreteBuilder
• Director
• Product

• Builder
• ConcreteBuilder
• Director
• Product

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Structure for Participants
Client
Product
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Builder Pattern Interaction
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When to use a Builder Pattern

• When the algorithm for building a complex object
  should be independent of the parts that make up
  the object and how theyre assembled
• When the construction process must allow
  different representations for the object thats
  constructed
• When building a composite structural object

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Key Consequence of Builder Pattern

• Vary a products internal representation
• Isolates code for construction and representation

Dont forget that the Builder Design Pattern also
gives you finer control over the construction
process!
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How to code a builder

• Assembly and Construction Interface
• No abstract class for products
• Empty methods as default in Builder

Class MazeBuilder Public virtual void
BuildMaze() virtual void BuildRoom(int
room) virtual void BuildDoor(int
roomFrom, int roomTo) virtual Maze
GetMaze() return 0 Protected
MazeBuilder()
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Other Creational Patterns

• Object Creation
• Abstract Factory
• Prototype
• Singleton
• Class Creation
• Factory Method

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Special Thanks

• Design Patterns. Elements of Reusable
  Object-Oriented Software
• Erich Gamma, Richard Helm, Ralph Johnson, John
  Vlissides
• Provider of Design Pattern powerpoint slides
  online. (http//vik.ktu.lt/moduliai/)
• Bob the Builder