Class<?> type for abstract classes in TypeScript-CodePudding

In TypeScript I use Java like type Class:

interface Class<T = void> {

    new(...args: any[]): T;

}

However, such type doesn't work with abstract classes:

abstract class Bar {}

class Foo {
   
  test(clazz: Class) { }

  doIt() {
    this.test(Bar);//ERROR
  }
}

The error I get is Argument of type 'typeof Bar' is not assignable to parameter of type 'Class<void>'. When class Bar is not abstract then everything is ok.

I understand, that the problem is that declaring Class we say it is possible to use new operator, but we can't use this operator for abstract classes. However, I need a type, that could be suitable both for non abstract and abstract classes (abstract classes are classes too). If it is possible, could anyone say how to do it?

CodePudding user response：

You can use an abstract construct signature:

type Class<T = void> =
  abstract new (...args: any[]) => T;

You can assign both a regular/concrete contructor and an abstract constructor to such a signature, as desired:

abstract class Bar { }
class Baz { }

class Foo {

  test(clazz: Class) { }

  doIt() {
    this.test(Bar); // okay
    this.test(Baz); // okay
  }
}

Note that, for whatever reason, abstract construct signatures must be in the form of an arrow construct expression (like a function expression); you can't put abstract before new in an object-like construct signature:

interface Oops<T = void> {
  abstract new(...args: any[]): T; // error!
  //~~~~~~ <-- 'abstract' modifier cannot appear on a type member
}

Playground link to code