Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.glorb.com!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail
From: cezary.tomczyk@gmail.com
Newsgroups: comp.lang.javascript
Subject: Re: Adding new method to existing object
Date: Sat, 17 Mar 2012 05:17:06 -0700 (PDT)
Organization: http://groups.google.com
Lines: 98
Message-ID: <23935524.6.1331986626075.JavaMail.geo-discussion-forums@vbla14>
References: <31786995.22.1331895413978.JavaMail.geo-discussion-forums@vbat19> <fe0320ca-41db-425e-8be2-dcec3878b903@v2g2000vbx.googlegroups.com>
NNTP-Posting-Host: 79.175.205.52
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
X-Trace: posting.google.com 1331986628 30867 127.0.0.1 (17 Mar 2012 12:17:08 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Sat, 17 Mar 2012 12:17:08 +0000 (UTC)
In-Reply-To: <fe0320ca-41db-425e-8be2-dcec3878b903@v2g2000vbx.googlegroups.com>
Complaints-To: groups-abuse@google.com
Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=79.175.205.52; posting-account=fqiM0AoAAACu3aIqzAK2xf9RRpymvKVH
User-Agent: G2/1.0
Xref: csiph.com comp.lang.javascript:12846

W dniu sobota, 17 marca 2012, 04:15:52 UTC+1 u=C5=BCytkownik Scott Sauyet n=
apisa=C5=82:
> CT wrote:
> > I want to extend my prototype object using another object. Just created=
 some example code:
> >
> > http://jsfiddle.net/u9e7R/13/
> >
> > Can someone explain me how can I extend existing prototype object using=
 new object?
>=20
> David Mark pointed out the basic flaw in your code, that you munged
> the constructor.  I posted a fairly minimal fix to that earlier.  (I
> apologize for posting only a link; I know that's poor citizenship on
> USENET.  I was in a hurry, but that's no excuse.)  But that version is
> to me still fundamentally flawed.  It's far too complicated for what
> it does.  Below is another version with nearly the same behavior, but
> significantly simpler code.
>=20
> There are two main differences in behavior: first, there is no factory
> function, just the plain constructor; and second, the addMethod
> function is attached to the constructor, not to the instances.  To me
> that simply makes sense, since it is updating the prototype.  If you
> meant this to apply to instances, the code would be far more simple.
>=20
> Here is the simplified code, also available at <http://jsfiddle.net/
> u9e7R/18/>

It's simpler, like I've done this before, but not on the jsFiddle. Next I j=
ust wanted to return an instance of an object.

>     //~ I just attach this to the global namespace here instead
>     //~ of using the `global` variable to reference `this`.
>=20
>     var JsCode =3D (function() {
>       var JsCode =3D function(params) {
>       };
>=20
>       //~ Could use your technique of assigning the prototype,
>       //~ but I don't see the point.  I just refer to it directly.
>       var proto =3D JsCode.prototype;
>=20
>       proto.test =3D function() {
>         console.log('Function test complete');
>         return this;
>       };
>=20
>       //~ Since this is added to the prototype, there is no
>       //~ need for a function to find the prototype of the object.
>       JsCode.addMethod =3D function (name, fn) {
>         var old =3D proto[name];
>=20
>         proto[name] =3D function() {
>           if ( fn.length =3D=3D arguments.length ) {
>             return fn.apply( this, arguments );
>           } else if ( typeof old =3D=3D=3D "function" ) {
>             // really need error checking here.
>             return old.apply( this, arguments );
>           }
>         };
>       };
>=20
>       return JsCode;
>=20
>     })();
>=20
>     var test2 =3D function() {
>       console.log('Function test2 complete');
>       return this;
>     };
>=20
>     JsCode.addMethod('test2', test2);
>=20
>     //~ Without the factory function, you must use `new`.
>     var jsc =3D new JsCode();
>     jsc.test2();  //~ or chain these as in the original
>     jsc.test();
>=20
>=20
> This does change the interface a little, but seems much cleaner.  If
> you really want a factory function, you could replace the `return`
> statement above with something like this:
>=20
>     var result =3D function(params) {
>       return new JsCode(params);
>     }
>     result.addMethod =3D JsCode.addMethod;
>     return result;
>=20
> (although that could be further simplified if desired.)
>=20
> Does this capture the essence of what you're trying to do?

Yes! Thank You for clarifying me. This is exactly what I wanted to achieve.

--=20
Regards,
CT