Add private class fields

[uMaxmaxmaximus]

You private props is not private:

1. The code is not written on the typescript (which accordingly is not subject to static analysis) can access them.

2. there is a naming conflict in the child classes (child classes can not use the same private properties of the parent class name, even though the conflict of names should not be)

SOLUTION:

compile this code

class Animal {
    private handlers = []
}

class Rebbit extends Animal {
    private handlers = []
}

to ES6:

class Animal {
    let _private_handlers = Symbol('Animal.handlers')

    constructor(){
        this[_private_handlers] = []
    }
}

class Rebbit extends Animal {
    let _private_handlers = Symbol('Rebbit.handlers')

   constructor(){
        this[_private_handlers] = []
    }
}

Simplified Symbol es5 pollyfill:

function Symbol(name){ return name + Math.random()  }

Yes, this is not in the semantics of the javascript, but then your private property modificator too is not in the semantics of the javascript, but you've added them as a convenience.

protected props

class Animal {
    protected handlers = []
}

class Rebbit extends Animal {
    protected handlers = []
}

compile to ES6:

class Animal {
    constructor(){
       this._handlers = []
    }
}

class Rebbit extends Animal {
    constructor(){
       this._handlers = []
    }
}

the only way it will not work, expressions like this[propName] because we need to know the name of the property to which the access, in advance at compile time, so if it is a private or protected, then replace it with the proper structure: private to this[symbol], protected to this._prop

[DanielRosenwasser]

Hey @uMaxmaxmaximus

1. That ES6 code isn't valid - you can't declare a let inside of a class. Perhaps you meant something like this entry in our FAQ.
2. We've looked into using Symbols for privates in Implement private variables, getter/setters and methods using Symbols #685 but it didn't turn out well.

In general this comes up every once in a while, but treating private members as members on the object itself seems to still be the best approach to use.

[uMaxmaxmaximus]

ok, i write coffeescript mod to (typescript and es6) and impliment private props, since you can not