allow calling class constructor as a function(without new)

[disjukr]

es2015 says "If F’s [[FunctionKind]] internal slot is "classConstructor", throw a TypeError exception."
but i don't know why.

i just wanted to make abstract class decorator using babel:

function abstract(target) { // decorator
    return function cls() {
        if (new.target === cls) {
            throw new Error('instantiating abstract class is disallowed');
        }
        target.call(this, ...arguments);
    }
}

@abstract class A {
    constructor() {
        console.log('a');
    }
}
class B extends A {
    constructor() {
        super();
        console.log('b');
    }
}

// new A(); // Error: instantiating abstract class is disallowed
new B(); // intended no error but it emits TypeError

call constructor proposal seems can't solve my problem.

[meandmycode]

Well, B is trying to extend A which is no longer a class after calling abstract but a function.. if you really want to do this, you could do the following:

function abstract(target) {
    return class cls extends target {

      constructor(...args) {

        if (new.target === cls) {
            throw new Error('instantiating abstract class is disallowed');
        }

        super(...args);

      }

    }
}

[meandmycode]

Well, B is trying to extend A which is no longer a class after calling abstract but a function.. if you really want to do this, you could do the following:

function abstract(target) {
    return class cls extends target {

      constructor(...args) {

        if (new.target === cls) {
            throw new Error('instantiating abstract class is disallowed');
        }

        super(...args);

      }

    }
}

[zenparsing]

This question is not appropriate for this repository. Please move this to the es-dicuss mailing list (and try looking at the archives as well).

[zenparsing]

This question is not appropriate for this repository. Please move this to the es-dicuss mailing list (and try looking at the archives as well).

[domenic]

Yes, please ask help questions on Stack Overflow or es-discuss. See https://github.com/tc39/ecma262/blob/master/CONTRIBUTING.md for what is acceptable to post to this repository.

[domenic]

Yes, please ask help questions on Stack Overflow or es-discuss. See https://github.com/tc39/ecma262/blob/master/CONTRIBUTING.md for what is acceptable to post to this repository.