Constructor? - Githubissues

I have concerns about constructors in mixins. Allowing declaring constructor in mixins means allowing access to super since it's a must to call super in constructor, which would lead to origin class reference leakage.

As I understand mixins, they adds own properties and methods and encapsulate logic acting like a plain JS object. But allowing a constructor somewhat equals them to classes, which is not that simple.

For initiating logic I would expect to have a dedicated keyword like init

mixin Network {
    online = false

    connect() {...}
    disconnect() {...}

    init {
        this.connect()
    }
}

In case of mixin extension, the extensions would just add up to this as they are a part of origin mixin since there could be multiple mixin extensions.

mixin Events {
    listeners = new Set

    dispatch() {...}
    on() {...}
}

mixin Socket extends Network {
    init {
        this.dispatch(...) // no access to `super` in mixins.
    }
}

tc39 / proposal-mixins

Constructor? #16