Subj : Re: define new function in Class String (Spidermonkey)
To   : netscape.public.mozilla.jseng
From : Blaubaer
Date : Wed Jan 05 2005 01:55 am

I want to add the function sprintf to the String type.
var a = new String();
a.sprintf("Integer: %d", 1);

My function sprintf works, an returns the result, but I also want to change 
the value of "a".

Thx Blaubaer

"Brendan Eich" <brendan@meer.net> schrieb im Newsbeitrag 
news:41DB3758.8090001@meer.net...
> Blaubaer wrote:
>> I want's to define a new function in jsstr.c and I want to change the 
>> value of the String.
>>
>> OBJ_GET_SLOT(cx, obj, JSSLOT_PRIVATE); works but:
>> OBJ_SET_SLOT(cx, obj, JSSLOT_PRIVATE, val); resets the value after 
>> leaving the funtion? :-(
>
> You don't want to do that.
>
> First, put extensions in separate files, and add your methods to the 
> object you get back in v from:
>
>     JSBool ok;
>     jsval v;
>     const char Sp[] = "String.prototype";
>
>     ok = JS_EvaluateScript(cx, global, Sp, sizeof Sp - 1, NULL, 0, &v);
>
> Second, by changing the private data of a String object wrapper, you are 
> not affecting the characters in the primitive type string value.  Nor can 
> you, for several good reasons including ECMA-262 and sharing sanity.
>
> Why do you think you want to mutate a string, anyway?
>
> /be

.