NewableFunction not working as intended

[rajmondx]

There is little info about NewableFunction except for the meeting notes in #27102 and the pr #27028.

As far as I understand the comments there, a NewableFunction should be "callable" with new Foo(...), right? Or do we have to stick with apply(...)/call(...)?

Example:

class Foo {}

function doSomething(clazz: NewableFunction) {
 new clazz();
 // This expression is not constructable.
 // Type 'NewableFunction' has no construct signatures
}



doSomething(Foo); // passes but would fail with "normal functions" aka. CallableFunction

Question about workaround:

If NewableFunction works as desired should we stick with new Function.prototype.bind.call(clazz, undefined); or should we define our own "ConstructableFunction" (a lot of people suggest this and even angular did it):

eg.

export interface ConstructableFunction extends NewableFunction {
 new(...args: any[]): any
}

[rajmondx]

Ended up using something like this:

interface ConstructableFunctionTyped<T> extends NewableFunction {
 new(...args: any[]): T;
}

export type ConstructableFunction = ConstructableFunctionTyped<any>;
export type Class = ConstructableFunctionTyped<Object>;