Subj : Re: define new function in Class String (Spidermonkey)
To   : Blaubaer
From : Brendan Eich
Date : Tue Jan 04 2005 04:39 pm

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

.