On 21/06/06, Ryan Gahl <[EMAIL PROTECTED]> wrote:
Nope... in fact this is one of the "dynamic" benefits of a prototype based
object system. Changing the prototype of the "class" function (the function
from which the other references are constructed), changes the state of all
instances automatically.
MyObject.prototype.bSwitch = true; is the correct way to achieve what you
are looking for. Why would you want to do this by using an instance of said
class? It seems to me you'd _want_ to _not_ have to know what instances are
floating around in your application, so the "class" function's prototype is
the natural place to make this change. In other words, you have 10 widgets
and a couple of flibbets, maybe a few woozles on your page, each of them
possibly containing N instances of MyObject. Why would you want to have to
know the name of one of those instances to set this switch across all of
them... see my point?
Actually by MyObjec.bSwitch I was not refering to an instance but the
the constructor. i.e. it's a Class or Static member of the global
MyObject object.
The constructor of a class is an object too and can be referenced and
have members
You can still say
var MyObject = Class.create();
MyObject.prototype = {
... other methods and properties
}
MyObject.bSwitch = false;
obj1 = new MyObject();
obj2 = new MyObject();
But MyObject.bSwitch will be global.
On 6/21/06, Andrew Tetlaw <[EMAIL PROTECTED]> wrote:
> I've always though the ptototype objects are not mutable after
> instances have been made. I.e. changes to prototypes will not update
> existing instances.
>
> I've always done this:
>
> Object.extend(MyObject, {bSwitch: false});
>
> then MyObjec.bSwitch can be set/got globally
>
>
> On 21/06/06, Sam <[EMAIL PROTECTED]> wrote:
> >
> >
> > I need a single boolean which would be "globally" accessible to all
> > instances of a class. Seems like the boolean should be in the class
> > prototype, but I was troubled by the difficulty of setting the prototype
> > boolean to true. Maybe I'm missing something?
> >
> > var MyObject = Class.create();
> >
> > MyObject.prototype = {
> > bSwitch: false,
> > ... other methods and properties
> > }
> >
> > var oMyOb1 = new MyObject();
> > var oMyOb2 = new MyObject();
> > alert(oMyOb1.bSwitch); // reports false
> > alert(oMyOb2.bSwitch); // reports false
> >
> > Now set the value of bSwitch to true so all the oMyObN's will see a true
> > value.
> >
> > I can see the following methods...
> >
> > // __proto__ works in Firefox/Safari but isn't available in IE...
> > oMyOb1.__proto__.bSwitch = true;
> >
> > alert(oMyOb1.bSwitch); // reports true
> > alert(oMyOb2.bSwitch); // reports true
> >
> > // This changes bSwitch for a single instance. Not in the prototype.
> > oMyOb1.bSwitch = true;
> >
> > alert(oMyOb1.bSwitch); // reports true
> > alert(oMyOb2.bSwitch); // reports false, not what we want.
> >
> > // Seems strange to me to reference the Class, but this works...
> > MyObject.prototype.bSwitch = true;
> > alert(oMyOb1.bSwitch); // reports true
> > alert(oMyOb2.bSwitch); // reports true
> >
> > // It's a little more satisfying to create a method to hide this
reference
> > to the class...
> >
> > MyObject.prototype = {
> > bSwitch: false,
> > setSwitch: function() {MyObject.prototype.bSwitch = true;}
> > }
> > // Now this works, and only requires a reference to a method on an
instance
> > oMyOb1.setSwitch();
> >
> > alert(oMyOb1.bSwitch); // reports true
> > alert(oMyOb2.bSwitch); // reports true
> >
> >
> > // I thought all objects had prototypes. Why doesn't this work?
> > oMyOb1.prototype.bSwitch = true; // error: oMyOb1 is not a function
> > Is there another method that I've missed? Did prototype.js extend
> > __proto__ to work in IE?
> >
> > Sam
> >
> > _______________________________________________
> > Rails-spinoffs mailing list
> > [email protected]
> >
http://lists.rubyonrails.org/mailman/listinfo/rails-spinoffs
> >
> >
> >
>
>
> --
> Andrew Tetlaw
> htp://tetlaw.id.au
> _______________________________________________
> Rails-spinoffs mailing list
> [email protected]
>
http://lists.rubyonrails.org/mailman/listinfo/rails-spinoffs
>
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htp://tetlaw.id.au
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