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
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
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.