Is there a better way to assign constructor parameter in Typescript?

Question

I have a class with a various set of optional parameters when instantiated. I would like to be sure that the user input ONLY the available parameters option, and also add a default value if nothing is passed.

I come with this

export enum HexagoneType {
  POINTY,
  FLAT
}

export interface HexagoneOptions {
  center?: Vector2;
  size?: number;
  color?: string;
  type?: HexagoneType;
}

export default class Hexagone {
  ctx: CanvasRenderingContext2D;
  center: Vector2;
  size: number;
  color: string;
  type: HexagoneType;

  constructor(ctx: CanvasRenderingContext2D, options?: HexagoneOptions) {
    this.ctx = ctx;
    this.center = (options && options.center) ? options.center : new Vector2();
    this.size = (options && options.size) ? options.size : 100;
    this.color = (options && options.color) ? options.color : "red";
    this.type = (options && options.type) ? options.type : HexagoneType.POINTY;
  }
}

But is there something shorter ?

We need to know what the code is intended to achieve. To help reviewers give you better answers, please add sufficient context to your question, including a title that summarises the purpose of the code. We want to know why much more than how. The more you tell us about what your code is for, the easier it will be for reviewers to help you. The title needs an edit to simply state the task, rather than your concerns about the code. — Toby Speight
– Toby Speight, Commented Mar 17, 2021 at 16:11

slepic · Accepted Answer · 2020-02-04 10:17:49Z

This is typical example of service locator anti pattern that should be refactored to builder pattern.

export class Hexagone {
  constructor(
    private ctx: CanvasRenderingContext2D,
    private center: Vector2,
    private size: number,
    private color: string,
    private type: HexagoneType
  ) {}
}

export class HexagoneBuilder {
  public center?: Vector2;
  public size?: number;
  public color?: string;
  public type?: HexagoneType;

  constructor(private ctx: CanvasRenderingContext2D) {}

  create() {
    return new Hexagone(
      this.ctx,
      this.center ?: new Vector2(),
      this.size ?: 100,
      this.color ?: "red",
      this.type ?: HexagonType.POINTY
    )
  }
}

Sorry if i made some syntax errors, I dont work with ts on daily basis, but you should get the idea...

cefn · Accepted Answer · 2021-03-16 22:13:46Z

How about this...

export enum HexagoneType {
  POINTY,
  FLAT
}


type Vector2 = readonly [number, number]

export interface HexagoneOptions {
  center: Vector2;
  size: number;
  color: string;
  type: HexagoneType;
}

export default class Hexagone {
  ctx: CanvasRenderingContext2D;
  center: Vector2;
  size: number;
  color: string;
  type: HexagoneType;

  constructor(ctx: CanvasRenderingContext2D, {
    center = [0,0],
    size=100,
    color="red",
    type=HexagoneType.POINTY
  }: HexagoneOptions) {
    this.ctx = ctx;
    this.center = center;
    this.size = size;
    this.color = color;
    this.type = type;
  }
}
```

Stack Exchange Network

Is there a better way to assign constructor parameter in Typescript?

2 Answers 2

You must log in to answer this question.

Hot Network Questions

Is there a better way to assign constructor parameter in Typescript?

2 Answers 2

You must log in to answer this question.

Related

Hot Network Questions