Subj : Re: How do I raise an exception?
To   : netscape.public.mozilla.jseng
From : Thomas Sondergaard
Date : Wed Aug 03 2005 02:30 pm

Brendan Eich wrote:

> If you want to make an instance of Error and throw it, you'll have to 
> get the value of the "Error" property of a properly initialized or 
> otherwise (lazy standard class resolution) configured global object, and 
> save it with a rooted pointer or jsval.
> 
> Then you can call this Error constructor function object reference with 
> the JS_CallFunctionValue API, to create the exception object you wish to 
> throw, passing appropriate arguments.  If that all works, set the new 
> exception object reference as the pending exception and return false.
> 
> /be

Does this look reasonable? I found it here: 
http://egachine.berlios.de/embedding-sm-best-practice/ar01s05.html#error-reporting

inline
JSBool
ejs_throw_error(JSContext* cx, JSObject* obj, const char* msg)
{
   JSString* jsstr;
   // if we get errors during error reporting we report those
   if ( ((jsstr=JS_NewStringCopyZ(cx, msg)))
        && (JS_AddNamedRoot(cx,&jsstr,"jsstr")) ) {
     jsval dummy;						
     // We can't use JS_EvaluateScript since the stack would be wrong
     JSFunction *func;
     JSObject* fobj;
     const char* fbody="throw new Error(msg);";
     const char* argnames[]={"msg"};
     if ((func=JS_CompileFunction(cx, obj, NULL,
				 1, argnames,
				 fbody, strlen(fbody),	
				 NULL, 0))) {
       // root function
       if ( ((fobj = JS_GetFunctionObject(func)))
	   && (JS_AddNamedRoot(cx, &fobj, "fobj")) ) {
	jsval args[]={STRING_TO_JSVAL(jsstr)};
	JS_CallFunction(cx, obj, func, 1, args, &dummy);
	JS_RemoveRoot(cx, &fobj);
       }
     }
     JS_RemoveRoot(cx,&jsstr);
   }

   return JS_FALSE;
}

.