Document that when extending Easel display classes you should explicitly call initialize()

[brandenhall]

If initialize is not explicitly called then all sorts of things go wonky due to the fact that initialize() is where the display classes setup their children array and get assigned their UID.

[mikechambers]

Should we have developers explicitly call initialize? or just explicitly call the super class constructor from the constructor of the extending class?

i.e.

function MyDisplayObject()
{
    DisplayObject.call(this);
}

MyDisplayObject.prototype = new DisplayObject();

Thoughts?

[tommoor]

That syntax is certainly neater than that used in the examples bundled with Easel at the moment. Are there any disadvantages over the current suggested?

Child.prototype = new Parent();
Child.prototype._super = Child.prototype.initialize;
Child.prototype.initialize = function() {
    this._super(); // call parent constructor
}

[gskinner]

I think that for now, we should address this with documentation. We can re-evaluate this for v0.4. See the Game example (Ship.js and SpaceRock.js) for a functional example of extending existing display objects.

[mikechambers]

The question is what do we document?

I think:

function MyDisplayObject()
{
    DisplayObject.call(this);
}

MyDisplayObject.prototype = new DisplayObject();

Is clearer and easier to understand than:

Child.prototype = new Parent();
Child.prototype._super = Child.prototype.initialize;
Child.prototype.initialize = function() {
    this._super(); // call parent constructor
}

It also requires less internal knowledge about how the base class is implemented.

However, perhaps there is a functional difference between the two that is not immediately obvious to me.

[mikechambers]

The question is what do we document?

I think:

function MyDisplayObject()
{
    DisplayObject.call(this);
}

MyDisplayObject.prototype = new DisplayObject();

is clearer and easier to understand than:

Child.prototype = new Parent();
Child.prototype._super = Child.prototype.initialize;
Child.prototype.initialize = function() {
    this._super(); // call parent constructor
}

It also requires less internal knowledge about how the base class is implimented.

However, perhaps there is a functional difference between the two that is not immediately obvious to me.

[mikechambers]

We are moving this to the 0.4.0 release, so we have some more time to discuss the issue (as well as what the recommended approach for inheritance is).

[gskinner]

I have added a tutorial that specifically addresses this. I'm also going to think further about the ParentClass.call() approach.