Properties set before constructor is called when using bindToController

[suedama1756]

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• Do you want to request a feature or report a bug?

BUG

• What is the current behavior?

When using bindToController properties are being set before the constructor is invoked.

• If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via
  https://plnkr.co or similar (you can use this template as a starting point: http://plnkr.co/edit/tpl:yBpEi4).

bindToController: {
    min: '@',
}

class MyController {
  private _min : number; 
  constructor() {
     this._min = 0;
  }

  get min() {
    return this._min;
  }

  set min(value : number) {
     this._min = value;
  } 
}

• What is the expected behavior?

Constructor should be called before properties are set.

• What is the motivation / use case for changing the behavior?

Behaviour in properties setters that rely on values initialized in the constructor fail.

• Which version of Angular, and which browser and OS does this issue affect? Did this work in previous
  versions of Angular? Please also test with the latest stable and snapshot versions.

Windows 7, TypeScript 1.8.2, chrome 49.0.2623.87, Angular 1.5.0

• Other information (e.g. detailed explanation, stacktraces, related issues, suggestions how to fix)

[suedama1756]

The constructor is called in the following lines after the properties have been set in nodeLinkFn.

var controllerResult = controller();
if (controllerResult !== controller.instance) {

The properties setters created using Object.defineProperty are invoked even though the constructor has not yet been invoked. This is problematic if the property setters rely on values initialized in the constructor (in my case throwing exceptions).

[gkalpak]

This actually a feature not a bug :)

We are binding the properties, so you can work right away from the constructor with them.
(Note: This only works with regular functions not classes (but your TypeScript Class obviously gets transpiled to a plain old ES5 constructor function).)

Maybe you could check if _min is undefined before assigning a default value in the constructor.

[suedama1756]

With respect, I would suggest breaking the semantics of classes is a BUG and not a feature. As ECMA 6 becomes standard with property getters and setters this type of issue will become more common. It is called a "constructor" after all and controllers in all other areas of angular would have their constructors called before any other interaction (AFAIK).

I understand that it is difficult to understand how many people may be relying on this "feature" and that changing the behavior would probably have to be supported through an option for backward compatibility.

My issue was not with the constructor throwing an error, it was with the property setter assuming the state of the object was initialized and valid (the specific code is not shown in the example).

[dpogue]

Maybe you could check if _min is undefined before assigning a default value in the constructor.

I think that would fail if you had something like this:

class MyController {
  private _min : number = 0;

  constructor() { }
}

The resulting JS automatically sets _min in the constructor function:

var MyController = (function () {
    function MyController() {
        this._min = 0;
    }
    return MyController;
}());

[suedama1756]

I appreciate people are taking time out to provide workarounds; however, I'm not really looking for a work around; to be frank, its a trivial issue to resolve and I probably shouldn't be writing Javascript if I can't workaround it:).

I'm simply here to report the bug, which I still class as a bug. An APIs success is measured on its consistency. Every special case goes against this; an effects productivity, controllers in angular everywhere else are dealt with as types (with constructors), they are not functions.

[drpicox]

As docs says in: https://docs.angularjs.org/api/ng/service/$compile :

Deprecation warning: although bindings for non-ES6 class controllers are currently bound to this before the controller constructor is called, this use is now deprecated. Please place initialization code that relies upon bindings inside a $onInit method on the controller, instead

May be it should be changed ASAP. ¿Is there any scheduled change yet?