By my reading, everything seems to be working how it's supposed to work. But
how it's "supposed to work" is very surprising to me. And it's not really E4X
that's producing the odd behavior, it's the == operator. I'll go ahead and post
the answer and explanation in my next message.
--- On Thu, 8/13/09, Gordon Smith <gosm...@adobe.com> wrote:
From: Gordon Smith <gosm...@adobe.com>
Subject: RE: [flexcoders] Re: *** So you think you know ActionScript? (Read
original post first) ***
To: "flexcoders@yahoogroups.com" <flexcoders@yahoogroups.com>
Date: Thursday, August 13, 2009, 6:54 PM
Does anybody want to try to figure out what the E4X spec says it
should do? It's certainly possible that the Player implementation of E4X is
doing it wrong.
Gordon Smith
Adobe Flex SDK Team
From:
flexcoders@yahoogroups.com [mailto:flexcod...@yahoogroups.com] On Behalf Of
Tracy
Spratt
Sent: Thursday, August 13, 2009 3:10 PM
To: flexcoders@yahoogroups.com
Subject: RE: [flexcoders] Re: *** So you think you know ActionScript?
(Read original post first) ***
Ok, if you
say so. What is the result of your investigation?
It gets
kind of complicated because AS does implicit toString() sometimes which can
hide what is really happening.
Do:
trace(xmlList
== null);
and
trace(xmlList
== “null”);
return
the same result?
Tracy
Spratt,
Lariat
Services, development services available
From: flexcoders@yahoogroups.com
[mailto:flexcod...@yahoogroups.com] On Behalf Of Dave Glasser
Sent: Thursday, August 13, 2009 5:22 PM
To: flexcoders@yahoogroups.com
Subject: RE: [flexcoders] Re: *** So you think you know ActionScript?
(Read original post first) ***
Actually,
no. It would interpret it as null if it were enclosed in curly braces like
this:
var xml:XML = <outer><inner>{null}</inner></outer>;
And even then, null might be converted to its String value, "null",
as the content of the element. I'd have to try it to know for sure.
In the example I gave, the content of the element is a String consisting of
the letters "n", "u", "l" and "l", in
that order.
In any case, the xmlList variable would reference a non-null XMLList object.
That's easily proven by dereferencing it:
trace("The length is " + xmlList.length());
That would output "The length is 1".
--- On Thu, 8/13/09, Tracy Spratt <tr...@nts3rd.com>
wrote:
From: Tracy Spratt <tr...@nts3rd.com>
Subject: RE: [flexcoders] Re: *** So you think you know ActionScript? (Read
original post first) ***
To: flexcoders@yahoogroups.com
Date: Thursday, August 13, 2009, 3:49 PM
Ah, I
see something I missed at first. This example is using “literal” xml,
so the null IS getting interpreted by AS as null and not as a string. I
bet it would be different if you did:
var
xml:XML = XML(“<outer><inner> null</inner> </outer>”);
Even so
I am still surprised because the null should be the text node and the
expression should return an XMLList with zero length. Very interesting.
Tracy
Spratt,
Lariat
Services, development services available
From:
flexcod...@yahoogro ups.com [mailto:flexcoders@ yahoogroups. com] On
Behalf Of jaywood58
Sent: Thursday, August 13, 2009 12:48 PM
To: flexcod...@yahoogro ups.com
Subject: [flexcoders] Re: *** So you think you know ActionScript?
(Read original post first) ***
--- In flexcod...@yahoogro ups.com, "Tracy Spratt"
< tracy @...> wrote:
>
> _____
>
> From: flexcod...@yahoogro ups.com [mailto:flexcod...@yahoogro
ups.com] On
> Behalf Of Paul Andrews
> Sent: Wednesday, August 12, 2009 9:33 PM
> To: flexcod...@yahoogro
ups.com
> Subject: Re: [flexcoders] *** So you think you know ActionScript? (Read
> original post first) ***
>
>
>
>
>
> Dave Glasser wrote:
> > Consider this code snippet:
> >
> > var xml:XML = <outer><inner> null</inner>
</outer>;
> > var xmlList:XMLList = xml.inner;
> > trace(xmlList == null);
> >
> > What does the trace statement output, true or false, and why?
> >
> > Please provide an answer without running the code (of course) and,
better
> yet, without consulting any documentation, or any of the other answers
that
> may have been posted already (if you read the list in chronological
order.)
> Pretend it's a job interview question and you have to give it your best
shot
> off the top of your head.
> >
> > And also, if you don't mind, don't top-post your answer, so that if
> someone does read your answer before the original post, they might get a
> chance to answer without having seen yours first.
> >
>
> xmlList is set to point at somthing which isn't a list, so I think the
> trace statement will not be reached. That's my 02:31AM thought..
>
>
>
> All e4x expressions return an XMLList. It can be empty but is never a
null.
> Besides, the characters. "null" in a text node are just a
string. "null" in
> an AS comparison is a special value. The trace will display false.
> Trace("xmllist. text() =="null" ); //would return true.
>
>
>
> Tracy Spratt,
>
> Lariat Services, development services available
>
Like Tracy , I thought it would return false, for the same reason -- that
<inner>null< /inner> would be interpreted as a string. Was
surprised when I ran the code and saw true. What's going on? It seems like
the AS decoder recognizes "null" as a special case.
