Implement method functionality within TypeScript interfaces

Question

Implement method functionality within TypeScript interfaces

I've encountered a scenario where I have an interface that will be utilized by multiple classes:

interface I {
  readonly id: string;
  process(): void;
}

My objective is to pass the id through a constructor like so:

class A implements I {...}
let a: A = {id: "my_id"} // or new A("my_id");

I'm looking for a way to avoid repeating the default constructor implementation in each class that implements the interface, for example:

class A implements I {
  constructor(id: string){ this.id = id }
}

Although I attempted to include the constructor implementation in the interface itself, I encountered a "cannot find id" error.

Is there a solution for this in TypeScript?

typescript

Answer 1

Answer №1

It is actually not possible, but you can find more information here.

One way to achieve similar results is by implementing the following code:

interface IMyInterface {
    readonly id: string;
    process(): void;
}

class ParentClass {
    id: string;
    constructor(id: string) {
        this.id = id;
    }
}

class SubClassOne extends ParentClass implements IMyInterface {
    process(): void {
        throw new Error('Method not implemented.');
    }
}
class SubClassTwo extends ParentClass implements IMyInterface {
    process(): void {
        throw new Error('Method not implemented.');
    }
}

const myclassOne = new SubClassOne('123');
const myclassTwo = new SubClassTwo('123');

Answer 2

It is actually not possible, but you can find more information here.

One way to achieve similar results is by implementing the following code:

interface IMyInterface {
    readonly id: string;
    process(): void;
}

class ParentClass {
    id: string;
    constructor(id: string) {
        this.id = id;
    }
}

class SubClassOne extends ParentClass implements IMyInterface {
    process(): void {
        throw new Error('Method not implemented.');
    }
}
class SubClassTwo extends ParentClass implements IMyInterface {
    process(): void {
        throw new Error('Method not implemented.');
    }
}

const myclassOne = new SubClassOne('123');
const myclassTwo = new SubClassTwo('123');

Implement method functionality within TypeScript interfaces

Answer №1

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