Subj : Re: referring to the "context node" in XML filtering predicate with
To   : Martin.Honnen
From : Brendan Eich
Date : Fri Apr 01 2005 10:44 pm

Martin Honnen wrote:
> 
> E4X section 11.2.4 describes the XML filtering predicate operator. In 
> the predicate I would like to call a method of the XML object the 
> filtering predicate is applied to e.g.
>   xmlObject..*.(nodeKind() == 'text')
> however both Rhino and Spidermonkey then tell me that nodeKind is not 
> defined. Is there any way to call a method in the predicate or is the 
> predicate only able to access non function properties (i.e. the child 
> elements by name or the attributes by @attributename)?


E4X has what I call a bug where method names are hidden from the normal
property lookup mechanism, even though the spec says they're
function-valued properties of XML.prototype and XMLList.prototype.  We
are talking about fixing this with a function namespace.

I've prototyped this in SpiderMonkey such that (with a fix just checked 
in today) the following works:

$ cat fn.js

xmlObject = <a><b>hi</b><b>there</b></a>

l = xmlObject..*.(function::nodeKind() == 'text' &&
                   print(function::toXMLString()))

$ Linux_All_DBG.OBJ/js -x fn.js
hi
there

The function reserved identifier, when used as a namespace prefix, 
identifies an internal namespace whose URI is guaranteed not to collide 
with any valid URI.  This namespace allows qualified access to function 
valued properties of XML.prototype (i.e., methods).

/be

.