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OOP vs FP (both with immutables)
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| interface IElement { | |
| state: string; | |
| temperature: number; | |
| warm: (degrees: number) => IElement; | |
| cool: (degrees: number) => IElement; | |
| deriveState: (temperature: number) => string; | |
| }; | |
| class WaterElement implements IElement { | |
| private _state = 'liquid'; | |
| private _temperature = 20; | |
| constructor(temperature: number = 20) { | |
| this._temperature = temperature; | |
| this._state = this.deriveState(temperature); | |
| } | |
| get state(): string { | |
| return this._state; | |
| } | |
| get temperature(): number { | |
| return this._temperature; | |
| } | |
| deriveState(temperature: number): string { | |
| if (temperature > 100) return 'gaseous'; | |
| if (temperature > 0 && temperature < 100) return 'liquid'; | |
| return 'solid'; | |
| } | |
| warm(degrees: number): IElement { | |
| const temperature = this.temperature + degrees; | |
| return new WaterElement(temperature); | |
| } | |
| cool(degrees: number): IElement { | |
| const temperature = this.temperature - degrees; | |
| return new WaterElement(temperature); | |
| } | |
| } | |
| const liquidWater = new WaterElement(20); | |
| const solidWater = liquidWater.cool(40); | |
| const steamWater = solidWater.warm(150); | |
| console.log(liquidWater.temperature, liquidWater.state); // 20 liquid | |
| console.log(solidWater.temperature, solidWater.state); // -20 solid | |
| console.log(steamWater.temperature, steamWater.state); // 130 gaseous | |
| function AlcoholElement(temperature: number = 20): IElement { | |
| const state = deriveState(temperature); | |
| function deriveState(temperature: number): string { | |
| if (temperature > 78) return 'gaseous'; | |
| if (temperature > -114 && temperature < 78) return 'liquid'; | |
| return 'solid'; | |
| }; | |
| function warm(degrees: number): IElement { | |
| const _temperature = temperature + degrees; | |
| return AlcoholElement(_temperature); | |
| } | |
| function cool(degrees: number): IElement { | |
| const _temperature = temperature - degrees; | |
| return AlcoholElement(_temperature); | |
| } | |
| const element = { | |
| deriveState, | |
| warm, | |
| cool | |
| }; | |
| Object.defineProperties(element, { | |
| temperature: { | |
| value: temperature, | |
| writable: false | |
| }, | |
| state: { | |
| value: state, | |
| writable: false | |
| } | |
| }); | |
| return element as IElement; | |
| } | |
| const liquidAlcohol = AlcoholElement(20); | |
| const solidAlcohol = liquidAlcohol.cool(240); | |
| const steamAlcohol = solidAlcohol.warm(450); | |
| console.log(liquidAlcohol.temperature, liquidAlcohol.state); // 20 liquid | |
| console.log(solidAlcohol.temperature, solidAlcohol.state); // -220 solid | |
| console.log(steamAlcohol.temperature, steamAlcohol.state); // 230 gaseous |
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