Something like properties

[Christoph Basedau]

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

[Martin Honnen]

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/

[Christoph Basedau]

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

[Martin Honnen]

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/