How to make a class implement a call signature in Typescript?

Question

I have defined the following interface in typescript:

interface MyInterface {
    () : string;
}

This interface simply introduces a call si

Answer 1

In case if callable interface should have other methods you can do it like this:

interface Greeter {
    (): void;
    setName(name: string): void;
}

class ConsoleGreeter {

    private constructor( // constructable via `create()`
        private name = 'world'
    ) {}

    public call(): void {
        console.log(`Hello ${this.name}!`);
    }

    public setName(name: string) {
        this.name = name;
    }

    public static create(): Greeter {
        const instance = new ConsoleGreeter();
        return Object.assign(
            () => instance.call(),
            {
                setName: (name: string) => instance.setName(name)
                // ... forward other methods
            }
        );
    }
}

const greeter = ConsoleGreeter.create();
greeter(); // prints 'Hello world!'
greeter.setName('Dolly');
greeter(); // prints 'Hello Dolly!'

Downside: greeter instanceof ConsoleGreeter is false