Subj : Re: why does it not print Hello twice?
To   : Jens Thiele <karme@unforgettable.com>
From : Brendan Eich <brendan@meer.net>
Date : Thu Apr 15 2004 01:08 am

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Jens Thiele wrote:
> I am stuck:
> 
> var w=function(text){
>         return (function(id,o,n){print(text);return n;});
> }("Hello");
> w();
> foo={x:1}
> foo.watch("x",w);
> foo.x=10;
> 
> Is watch somehow different?
> Is it a bug?

Yes and yes.  Thanks again, this is a very old bug!  I'm filing 
http://bugzilla.mozilla.org/show_bug.cgi?id=240577 and fixing now, using 
the attached patch.

/be

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Index: jsobj.c
===================================================================
RCS file: /cvsroot/mozilla/js/src/jsobj.c,v
retrieving revision 3.158
diff -p -u -8 -r3.158 jsobj.c
--- jsobj.c	14 Apr 2004 02:36:37 -0000	3.158
+++ jsobj.c	15 Apr 2004 07:05:02 -0000
@@ -1261,36 +1261,42 @@ obj_watch_handler(JSContext *cx, JSObjec
     ok = js_InternalCall(cx, obj, OBJECT_TO_JSVAL(funobj), 3, argv, nvp);
     StopResolving(cx, &key, JSRESFLAG_WATCH, entry, generation);
     return ok;
 }
 
 static JSBool
 obj_watch(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
 {
+    JSObject *funobj;
     JSFunction *fun;
     jsval userid, value;
     jsid propid;
     uintN attrs;
 
-    fun = js_ValueToFunction(cx, &argv[1], 0);
-    if (!fun)
-        return JS_FALSE;
-    argv[1] = OBJECT_TO_JSVAL(fun->object);
+    if (JSVAL_IS_FUNCTION(cx, argv[1])) {
+        funobj = JSVAL_TO_OBJECT(argv[1]);
+    } else {
+        fun = js_ValueToFunction(cx, &argv[1], 0);
+        if (!fun)
+            return JS_FALSE;
+        funobj = fun->object;
+    }
+    argv[1] = OBJECT_TO_JSVAL(funobj);
 
     /* Compute the unique int/atom symbol id needed by js_LookupProperty. */
     userid = argv[0];
     if (!JS_ValueToId(cx, userid, &propid))
         return JS_FALSE;
 
     if (!OBJ_CHECK_ACCESS(cx, obj, propid, JSACC_WATCH, &value, &attrs))
         return JS_FALSE;
     if (attrs & JSPROP_READONLY)
         return JS_TRUE;
-    return JS_SetWatchPoint(cx, obj, userid, obj_watch_handler, fun->object);
+    return JS_SetWatchPoint(cx, obj, userid, obj_watch_handler, funobj);
 }
 
 static JSBool
 obj_unwatch(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval)
 {
     return JS_ClearWatchPoint(cx, obj, argv[0], NULL, NULL);
 }
 

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