On 13.06.2011 1:43, Dmitry A. Soshnikov wrote:
On 13.06.2011 1:18, Brendan Eich wrote:
On Jun 12, 2011, at 2:22 AM, Irakli Gozalishvili wrote:
Hi,
Is there anything else (other than starting this thread) I can do to
make committee consider `Function.prototype.extend` as an
alternative to a proposed class sugar ?
Could you show Function.prototype.extend again, and say how it solves
the super-construct and super-method-call problems?
If interested, I know at least three versions of normal `super` sugar
in ES3 code:
1. using wrappers for every descendant method with the same name (the
technique is to (a) set `this.super` to parent, (b) activate parent
method and get result, (c) return result to child)
2. using `Object.prototype` to store `super`
3. using `arguments.caller` (banned in ES5-strict, non-standard in
ES3, but I normally used it in my projects)
If will be needed, I can write the code for all three techniques (the
later though can be found here:
https://github.com/DmitrySoshnikov/def.js/blob/master/def.js#L80
Forgot to mention example:
def ("Person") ({
init: function (name) {
this.name = name;
},
speak: function (text) {
alert(text || "Hi, my name is " + this.name);
}
});
def ("Ninja") << Person ({
init: function (name) {
this.base(name);
},
kick: function () {
this.speak("I kick u!");
}
});
var ninjy = new Ninja("JDD");
ninjy.speak();
ninjy.kick();
Dmitry.
That is, it's not actually the main issue, we normally can write in
ES3/5 code something like this:
var Foo = Class({
constructor: function (a) {
this.a = a;
},
activate: function () {
return this.a;
}
});
var Bar = Class({
constructor: function (a, b) {
this.super(a);
this.b = b;
},
activate: function () {
console.log(this.b + this.super());
}
});
var bar = new Bar(10, 20);
bar.activate(); // 30!
P.S.: of course this.super() is much more convenient than (real code
from e.g. ExtJS) `Bar.superclass.constructor.apply(this, arguments)`
(what? are you kidding me, guys? Seems you just like syntactic noise).
But unfortunately because of hack-nature (`caller` is not-standard and
banned, people afraid to augment `Object.prototype`, wrappers are not
so efficient), so it's not e.g. for cross-browser code. Though, I was
pleased to use it in my library in the project where I had
SpiderMonkey-only stuff (patched Thunderbird), so there I used that
`this.super` actively (OK, actually `this._super`, because only since
ES5 we can use keywords as properties).
However, regardless that we _can_ implement convinient and sugared
super calls as a library, classes from the box will be more convenient
IMO.
Dmitry.
/be
Thanks
--
Irakli Gozalishvili
Web: http://www.jeditoolkit.com/
Address: 29 Rue Saint-Georges, 75009 Paris, France
<http://goo.gl/maps/3CHu>
On Tuesday, 2011-05-24 at 24:48 , Brendan Eich wrote:
On May 23, 2011, at 11:25 AM, Bob Nystrom wrote:
One thing I'd like the proposal to support, which it doesn't
currently, is initializers on instance property declarations. Then
you could do:
class C {
public _list = [];
}
With that, you'll correctly get a new _list on each instance of C
when it's created.
But (we've argued, I forget where so repeating it here), this looks
like [] is evaluated once when the class declaration is evaluated.
That is not what you intend.
Then at some point (in the last thread on this) I remembered
parameter default values, but they cover only missing parameters to
the constructor. This _list member could be private. But it has to
be initialized in a body that executes once per instantiation,
which is not the class body -- it's the constructor body.
/be
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