Subj : Callbacks from C/JS
To   : netscape.public.mozilla.jseng
From : Andreas Podgurski <Andreas.Podgurski@WAM.de>
Date : Mon Feb 16 2004 11:19 pm

Hi!
I'm wondering, what is the standard way to declare a callback mechanism 
with the JS-Interface? My plan would be to have a method in the calling 
object (There is the possibility to have several callbacks on one hook) 
which adds the callback, kind of

function MyCallback()
{

}

MyObject.AddCallback(MyCallback);

and something similar in the C-Interface

JSBool MyCallback(JSContext *lpContext,JSObject *lpObject,uintN 
argc,jsval *argv,jsval *rval)
{

	return (JS_TRUE);
}

argv[0]=JS_NewFunction(lpContext,MyCallback,2,0,NULL,"MyCallback");
JS_CallFunctionName(lpContext,lpObject,"AddCallback",1,argv,&Res);

But there are some problems or misunderstandings I run into. First, I 
don't understand, if I need to convert the JSFunction * into an object 
via JS_GetFunctionObject or do I pass the JSFunction * directly? How can 
I determine the datatype, if it is a function? I havn't found a 
JSVAL_IS_FUNCTION in the jsref.pdf. Maybe I'm on the wrong way at all, 
but I don't want to use a "mini-script" approach like in the 
web-browsers (onMouseover="scriptcall();"), because I want to limit the 
possibilities to functions for internal reasons.

Thanks in advance,
Andreas Podgurski

.