Ok, I think I got it (if the indentation's funky, it's just so I can
collapse functions and they line up, so I still get a sense of where
classes start and end, as I had with the Class.create method):
function Behaviours () {
this.array = [];
}
Behaviours.prototype.push = function
(behaviour) {
this.array.push(behaviour);
}
Behaviours.prototype.list = function () {
$A(this.array).each(function(behaviour)
{
alert(behaviour);
});
}
function Person(name) {
this.name = name;
this.behaviours = new Behaviours();
}
function Man (name) {
Person(name);
this.behaviours.push('eat');
}
Man.prototype = new Person();
function Woman (name) {
Person(name);
this.behaviours.push('talk');
}
Woman.prototype = new Person();
On Jan 19, 11:27 am, iporter <[EMAIL PROTECTED]> wrote:
> Rob, I think I'm going to use the class.prototype.method syntax. I'm
> pretty sure it's still more verbose, but I want to use the same class
> definitions in the same .js file on the client and server sides, and
> it seems I can't if the class is a global variable, instead of a
> function
> (seehttp://groups.google.com/group/rubyonrails-spinoffs/browse_frm/thread...
> if interested).
>
> How does one acheive the effect of $super if not using Prototype's
> Class class?
>
> Cheers,
> Iain
>
> On Jan 18, 7:13 am, RobG <[EMAIL PROTECTED]> wrote:
>
> > On Jan 18, 2:30 am, iporter <[EMAIL PROTECTED]> wrote:
>
> > > In the below code, I expect two alerts '1 : 1' and then '1 : 1', but
> > > in reality I get '1 : 1' and '2 : 1'. For some reason, the
> > > declaration of the second object of class myClass alters the first
> > > object of the same class. However, it only alters
> > > 'this.options.value', and not 'this.value'. Can you tell me why this
> > > behaviour occurs, and how to resolve it?
>
> > > Cheers
>
> > > ---------------------------------------------------------------------------
> > > var myClass = Class.create({
> > > options:{},
> > > value: false,
> > > initialize: function(options) {
> > > this.options.value = options.value;
> > > this.value = options.value;
> > > },
> > > myAlert:function() {
> > > alert(this.options.value + ' : ' + this.value);
> > > }
>
> > > });
>
> > > var classObj1 = new myClass({value:1});
> > > classObj1.myAlert();
> > > var classObj2 = new myClass({value:2});
> > > classObj1.myAlert();
>
> > I think you are better off to understand what is actually happening.
> > Javascript does not have classes - it isn't an object oriented
> > language, it's object based. It uses prototypes for inheritance, not
> > classic OO inheritance.
>
> > While you can paper over the differences, they are still there. Two
> > features that often cause issues are the this keyword and closures,
> > which have combined here to cause an unexpected result.
>
> > To write your "class" (it's actually a javascript constructor, but
> > whatever) using plain javascript, you would write something like:
>
> > function MyClass(obj) {
> > this.value = obj.value;}
>
> > MyClass.prototype.options = {};
> > MyClass.prototype.showValue = function(){
> > alert(this.options.value + ':' + this.value);
>
> > }
>
> > That's it. Note that this takes less code than using Class.create().
> > Now if you test this:
>
> > var x = new MyClass({value:1});
> > x.showValue(); // --> 1:1
>
> > var y = new MyClass({value:2});
> > x.showValue(); // --> 2:1
>
> > You get the result you didn't want - the options object is shared by
> > all instances of MyClass because it is a property of the constructor's
> > prototype. If you want each instance of MyClass to have its own
> > options object, you add it in the constructor:
>
> > function MyClass(obj) {
> > this.value = obj.value;
> > this.options = {};
> > this.options.value = this.value; // or obj.value;}
>
> > MyClass.prototype.showValue = function(){
> > alert(this.options.value + ':' + this.value);
>
> > }
>
> > Now when you create some instances:
>
> > var x = new MyClass({value:1});
> > x.showValue(); // --> 1:1
>
> > var y = new MyClass({value:2});
> > x.showValue(); // --> 1:1
> > y.showValue(); // --> 2:2
>
> > Is that what you wanted? To me, the above is much simpler and clearer
> > than using Class.create, and is less code.
>
> > --
> > Rob
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