Subj : Re: Confused about enumerating
To   : netscape.public.mozilla.jseng
From : Brian Genisio <BrianGenisio@yahoo.com>
Date : Wed Feb 18 2004 10:20 am

Brendan Eich wrote:

> See JSCLASS_NEW_ENUMERATE and read jspubtd.h for a different approach 
> that does not require you to set properties at the start of the 
> enumeration.  However, it's always good to make what for..in discloses 
> match what can be accessed on a "get by get" basis, if you know the 
> ids.  IOW, all enumerable properties should appear to be properties, 
> even if they're reflected from private data using some kind of shared 
> (JSPROP_SHARED) prototype getter, e.g.
> 
> /be

Wonderful... using JSCLASS_NEW_ENUMERATE works like a charm... except 
when I return a property name that already exists.

See, the object is much like an array, so the length property is defined 
with the object, so myCollection.length is retrieved correctly.

If, I enumerate the values of myCollection, the first thing I want to 
return is the length... so I do the following:

JS_ValueToId(cx, STRING_TO_JSVAL(JS_InternString(cx, "length")), idp);

In this case, the for..in loop gets an empty string.  If instead, I set 
the jsid with a slightly different spelling:

JS_ValueToId(cx, STRING_TO_JSVAL(JS_InternString(cx, "Length")), idp);

It works fine.

Any ideas to why this is?

Brian

.