change Widget system inheritence to prototypal mixin

[psowden]

The inheritence chain for a widget should descend from Widget into the specific implementation like so:

Widget -> Menu -> DomMenu? -> HtmlMenu?

The render specific Widget classes (DomWidget?, HtmlWidget?...) will be defined as interfaces which get "mixed in" to the corresponding Dom*, Html*... object's prototypes.

This will hopefully allow us to:

• have a single defined interitence chain
• allow us to check for instances of both Widget and Menu
• allow us to call superclass methods in our *Menu chain
• still reap the benefits of abstracting to *Widget

[morris_dojo73@…]

An example of a tidy way to do super() or base() using this.inherited(arguments); - there is a lot of other meta junk in there sorry, the key function is declared inherited : function... Discussed with Bill. Not sure if useful, but have a squiz! Cheers, Morris.

[morris_dojo73@…]

Oh, the reason it is tidy is because it works using the prototype chain.

Trick 1: defining superProto on each method eg.

function someMethod() {};
someMethod.superProto = SuperClass.prototype;
someMethod.Meta$$functionName = 'someMethod';

Trick 2: calling the superclass (done more generically in inherited by getting caller function from args) - rolled out a call to super() looks like:

function someMethod() {
  // call super()
  arguments.callee.superProto[arguments.callee.Meta$$functionName].call(this);
}

Note - no references to classnames!

Using the inherited function declared in the attached file it looks like:

function someMethod() {
  // call super()
  this.inherited(arguments);
}

Or you could rewrite inherited(), and rename it to base (C++ style!) it looks like:

function someMethod() {
  // call super()
  base(this, arguments);
}

Caveats:

a) You need to define superProto on every method of the class - perhaps in extends() - this only occurs once when the class prototype is first constructed.

b) A function can only be used in one prototype. You cannot 'share' the same function between two prototypes i.e. you cannot go Class1.prototype.methodx = Class2.prototype.methody; (two references to same function). This is because the function object can only have one superProto attribute and one functionName attribute!

Anyway, thought it might be useful. Give me an email even if just to flame me!

Cheers, Morris.

[alex]

moving to widget release

[sjmiles]

I'm closing this tag because I believe we have settled on a widget inheritance structure now.

There are open questions wrt to what sort of OOP methods should be employed, but that is a separate question.

[anonymous]

Milestone 0.4 deleted