How to specify any newable type in TypeScript?

问题

I tried with this but it doesn't work. Foo is just a test of what works. Bar is the real try, it should receive any newable type but subclasses of Object isn't valid for that purpose.

class A {

}
class B {
    public Foo(newable: typeof A):void {

    }
    public Bar(newable: typeof Object):void {

    }
}

var b = new B();
b.Foo(A);
b.Bar(A); // <- error here

回答1:

You can use { new(...args: any[]): any; } to allow any object with a constructor with any arguments.

class A {

}

class B {
    public Foo(newable: typeof A):void {

    }

    public Bar(newable: { new(...args: any[]): any; }):void {

    }
}

var b = new B();
b.Foo(A);
b.Bar(A);  // no error
b.Bar({}); // error

回答2:

If you want to enforce only certain newables, you can specify the constructor's return type

interface Newable {
  errorConstructor: new(...args: any) => Error; // <- put here whatever Base Class you want
}

equivalent

declare class AnyError extends Error { // <- put here whatever Base Class you want
  // constructor(...args: any) // you can reuse or override Base Class' contructor signature
}

interface Newable {
  errorConstructor: typeof AnyError;
}

testing

class NotError {}
class MyError extends Error {}

const errorCreator1: Newable = {
  errorConstructor: NotError, // Type 'typeof NotError' is missing the following properties from type 'typeof AnyError': captureStackTrace, stackTraceLimitts
};

const errorCreator2: Newable = {
  errorConstructor: MyError, // OK
};

来源：https://stackoverflow.com/questions/33224047/how-to-specify-any-newable-type-in-typescript

标签

typescript

method-signature

newable