Builder Design Pattern

Video Lecture

Section	Video Links
Builder Pattern
Builder Use Case

Overview

...Refer to Book or Videos for extra content.

Terminology

...Refer to Book or Videos for extra content.

Builder UML Diagram

Builder Pattern Overview

Source Code

...Refer to Book or Videos for extra content.

./src/builder/builder-concept.ts

// Builder Concept Sample Code
class Product {
    parts: string[] = []
}

interface IBuilder {
    buildPartA(): this
    buildPartB(): this
    buildPartC(): this
    getResult(): Product
}

class Builder implements IBuilder {
    // The Concrete Builder
    product: Product

    constructor() {
        this.product = new Product()
    }

    buildPartA() {
        this.product.parts.push('a')
        return this
    }

    buildPartB() {
        this.product.parts.push('b')
        return this
    }

    buildPartC() {
        this.product.parts.push('c')
        return this
    }

    getResult() {
        return this.product
    }
}

class Director {
    // The Director, building a complex representation

    static construct() {
        'Constructs and returns the final product'
        return new Builder()
            .buildPartA()
            .buildPartB()
            .buildPartC()
            .getResult()
    }
}

// The Client
const PRODUCT1 = Director.construct()
console.log(PRODUCT1.parts)

Output

node ./dist/builder/builder-concept.js
[ 'a', 'b', 'c' ]

Builder Use Case

...Refer to Book or Videos for extra content.

Example UML Diagram

Builder Pattern in Context

Source Code

./src/builder/client.ts

// House Builder Example Code

import IglooDirector from './igloo-director'
import CastleDirector from './castle-director'
import HouseBoatDirector from './houseboat-director'

const IGLOO = IglooDirector.construct()
const CASTLE = CastleDirector.construct()
const HOUSEBOAT = HouseBoatDirector.construct()

console.log(IGLOO.construction())
console.log(CASTLE.construction())
console.log(HOUSEBOAT.construction())

./src/builder/igloo-director.ts

// A Director Class
import House from './house'
import HouseBuilder from './house-builder'

export default class IglooDirector {
    static construct(): House {
        // Note that in this IglooDirector, it has omitted the
        // set_number_of windows call since this Igloo will have
        // no windows.
        return new HouseBuilder()
            .setBuildingType('Igloo')
            .setWallMaterial('Ice')
            .setNumberDoors(1)
            .getResult()
    }
}

./src/builder/castle-director.ts

// A Director Class
import House from './house'
import HouseBuilder from './house-builder'

export default class CastleDirector {
    static construct(): House {
        return new HouseBuilder()
            .setBuildingType('Castle')
            .setWallMaterial('Sandstone')
            .setNumberDoors(100)
            .setNumberWindows(200)
            .getResult()
    }
}

./src/builder/houseboat-director.ts

// A Director Class
import House from './house'
import HouseBuilder from './house-builder'

export default class HouseBoatDirector {
    static construct(): House {
        return new HouseBuilder()
            .setBuildingType('House Boat')
            .setWallMaterial('Wood')
            .setNumberDoors(6)
            .setNumberWindows(8)
            .getResult()
    }
}

./src/builder/house-builder.ts

import House from './house'

interface IHouseBuilder {
    house: House
    setBuildingType(buildingType: string): this
    setWallMaterial(wallMaterial: string): this
    setNumberDoors(number: number): this
    setNumberWindows(number: number): this
    getResult(): House
}

export default class HouseBuilder implements IHouseBuilder {
    house: House

    constructor() {
        this.house = new House()
    }

    setBuildingType(buildingType: string): this {
        this.house.buildingType = buildingType
        return this
    }

    setWallMaterial(wallMaterial: string): this {
        this.house.wallMaterial = wallMaterial
        return this
    }

    setNumberDoors(number: number): this {
        this.house.doors = number
        return this
    }

    setNumberWindows(number: number): this {
        this.house.windows = number
        return this
    }

    getResult(): House {
        return this.house
    }
}

./src/builder/house.ts

// The Product

export default class House {
    doors = 0
    windows = 0
    wallMaterial = ''
    buildingType = ''

    construction(): string {
        return `This is a ${this.wallMaterial} ${this.buildingType} with ${this.doors} door(s) and ${this.windows} window(s).`
    }
}

Output

node ./dist/builder/client.js
This is a Ice Igloo with 1 door(s) and 0 window(s).
This is a Sandstone Castle with 100 door(s) and 200 window(s).
This is a Wood House Boat with 6 door(s) and 8 window(s).

Summary

...Refer to Book or Videos for extra content.

	Zabbix
	Grafana
	Prometheus
	Threejs and TypeScript
	SocketIO and TypeScript
	Blender Topological Earth
	Sweet Home 3D
	Design Patterns Python
	Design Patterns TypeScript

	Course Coupon Codes

Three.js and TypeScript
		Kindle Edition $9.99 $14.99 Paperback $29.99 $34.99
Design Patterns in TypeScript
		Kindle Edition $9.99 $14.99 Paperback $19.99 $24.99
Design Patterns in Python
		Kindle Edition $9.99 $14.99 Paperback $19.99 $24.99