«

Hi,


function F()
{
var m_flag = 42;
this.Flag = m_flag;
this.SetFlag = function(val){m_flag = val;}
this.GetFlag = function(){return m_flag;}
}

var f = new F();
alert(f.Flag + ' ' + f.GetFlag());
f.SetFlag(-13);
alert(f.Flag + ' ' + f.GetFlag());


Can one somehow let 'Flag' always return the *current* value
of m_flag *without* out using a function?
Somethin like a property Get/Put in VB/COM so you can write
f.Flag = -13;
var myFlag = f.Flag; // return -13
?

--
Gruesse, Christoph

Rio Riay Riayo - Gordon Sumner, 1979

Christoph Basedau wrote:


> function F()
> {
> var m_flag = 42;
> this.Flag = m_flag;
> this.SetFlag = function(val){m_flag = val;}
> this.GetFlag = function(){return m_flag;}
> }
>
> var f = new F();
> alert(f.Flag + ' ' + f.GetFlag());
> f.SetFlag(-13);
> alert(f.Flag + ' ' + f.GetFlag());
>
>
> Can one somehow let 'Flag' always return the *current* value
> of m_flag *without* out using a function?
> Somethin like a property Get/Put in VB/COM so you can write
> f.Flag = -13;
> var myFlag = f.Flag; // return -13
> ?

ECMAScript edition 3 does not know properties with getters/setters but
JavaScript 1.5 (in Spidermonkey, the engine used in Mozilla browsers)
implements them as follows as an extension to the standard:

function F (flag) {
this.flag = flag;
}
F.prototype.__defineGetter__ ('flag',
function () {
return this._flag;
}
);
F.prototype.__defineSetter__('flag',
function (flag) {
return this._flag = flag;
}
);

var f = new F('Kibo');
alert(f.flag);
alert(f.flag = 'Xibo');


--

Martin Honnen
http://JavaScript.FAQTs.com/

18.04.2005 13:22, Martin Honnen schrieb:
>
> Christoph Basedau wrote:>

[Getter/Setter-Properties in Javascript]

> ECMAScript edition 3 does not know properties with getters/setters but
> JavaScript 1.5 (in Spidermonkey, the engine used in Mozilla browsers)
> implements them as follows as an extension to the standard:
>
> function F (flag) {
> this.flag = flag;
> }
> F.prototype.__defineGetter__ ('flag',
> function () {
> return this._flag;
> }
> );
> F.prototype.__defineSetter__('flag',
> function (flag) {
> return this._flag = flag;
> }
> );
>
> var f = new F('Kibo');
> alert(f.flag);
> alert(f.flag = 'Xibo');

Thanks a lot Martin,

Spidermonkey properties work fine. Is JS 1.5, and especially this part,
going to be standardized in the near future, or will it likely remain a
Mozilla extension?



--
Gruesse, Christoph

Rio Riay Riayo - Gordon Sumner, 1979

Christoph Basedau wrote:

> Spidermonkey properties work fine. Is JS 1.5, and especially this part,
> going to be standardized in the near future, or will it likely remain a
> Mozilla extension?

JavaScript 1.5 implements the ECMAScript edition 3 standard but
getters/setters are an extension which is intentionally implemented in
this __defineGetter__/__defineSetter__ way to not conflict with any
syntax changes future ECMAScript editions might specify.
As for future ECMAScript editions I am not sure anything is going to
happen in this regard, there was work on an ECMAScript edition 4 in the
past with the main feature to introduce a class construct but no
standard resulted from that, instead Microsoft went ahead with
JScript.NET and Macromedia with ActionScript supporting classes.

--

Martin Honnen
http://JavaScript.FAQTs.com/