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Builder DesignPatterns

By:

PAWAN R NAIK

1MS09IS066

ISE 8 B

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One of the Creational Pattern

Intent:

Separates the construction of a complex object from

its representation so that the same construction

process can create different representations.

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Creational Design Patterns

Abstract instantiation process

Flexibility in whats created, who creates it, how its

created and when it is created.

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.

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Participants in Builder Pattern

Builder

ConcreteBuilder

Director

Product

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Product

ConcreteBuilder

buildPartA()

buildPartB()

getResult()

Director

construct()

Builder

buildPartA()buildPartB()

Client

for all parts in structure

{

builder->buildPart()

}

Structure for Participants

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Builder Pattern Interaction

Client Director ConcreteBuilder

new ConcreteBuilder

new Director(aConcreteBuilder)

construct() buildPartA()

buildPartB()

buildPartC()

getResult()

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Builder pattern interaction example

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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 differentrepresentations 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.

greater control over construction process

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DisadvantageRequires creating a separate ConcreteBuilder for each

different type of Product.

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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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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/).

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THANK YOU!