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Subject: Re[3]: [cgmo-webcgm] 5.7.10 Interface WebCGMEvent Example


Being short of time, I was doing trial and error to make the examples 
(Event and EventListener) work.  Using WinXP, IE6, and Itedo Beta 5:

"var cgmDoc;" -- did not work (JS object failure).

"var cgmDoc = new Object();"  -- worked.

"var cgmDoc = new WebCGMMetafile();"  -- worked.

Now that I have a bit more time, I'm interested to hear the resolution of 
the questions you raise.  I'm not a JS/ES expert, but have to go back to my 
reference book to sort out this stuff.  Any guru out there have the answer 
for us?

(We *do* need to sort it out, as it will need correction in W3C processing.)

-Lofton.

At 12:10 PM 11/29/2005 -0500, Benoit Bezaire wrote:
>Hi Lofton,
>
> From my understanding of ECMA-262.
>
>var cgmDoc;
>
>Is an uninitialized variable (actually initialized to 'undefined');
>
>var cgmDoc = new WebCGMMetafile();
>
>Has an additional Initializer ( = new WebCGMMetafile();) the variable
>is created (like above) when the scope is entered but assigned a
>value when the variable statement is executed.
>
>In this case, because 'WebCGMMetafile' is not an known Object, the new
>will throw a TypeError exception.
>
>You need to call getWebCGMMetafile(); to create a WebCGMMetafile
>Object. Doing:
>
>var cgmDoc = new Object();
>
>gains you nothing (that I can see), since it will be re-assigned by
>the getWebCGMMetafile(); call.
>
>That's my understanding, if someone has a different opinion, please
>share it with the group.
>
>--
>  Benoit   mailto:benoit@itedo.com
>
>
>Tuesday, November 29, 2005, 11:39:04 AM, you wrote:
>
> > At 11:16 AM 11/29/2005 -0500, Benoit Bezaire wrote:
> >><snip>
> >>
> >> >>   If other vendors are able to interpret such ecmascript, maybe they
> >> >>   can say so.
> >>
> >> > Curious that you ask the question.  One reason I didn't catch the 
> error is
> >> > that your beta (b4 and b5) code executes both examples successfully, 
> on my
> >> > WinXP with IE6.  (Have you subsequently changed the code so that the
> >> > invalid case fails?).  I *did* execute each example before 
> submitting the
> >> > text for CS ballot.
> >>Are you sure you haven't changed var cgmDoc; to var cgmDoc = new
> >>WebCGMMetafile(); between trying the test and publishing?
>
> > Well ... now I'm confused.  Both the listing in the CS text, and the code
> > in the .html file (as shown by "View Source" after executing the html) say:
>
> > <script type="text/ecmascript">
> >      var cgmDoc = new WebCGMMetafile();
> >      function handleClick(evt) {
> >      ....
>
> > Neither of them say "var cgmDoc;".  Your original question (previous
> > message) was:
>
> >>  Is var cgmDoc = new WebCGMMetafile(); valid?
>
> > (And my answer was, "not valid, because the constructor function is not
> > defined."  Now ... I don't know what JS or ECMAScript say about that case,
> > if the constructor definition is missing.  Does it substitute "new
> > Object()"?  Fail in unpredictable ways?  Other?)
>
> >>I just don't see how our implementation could create such an object.
> >>I'll have to get back to you on this.
>
> > Does JS/ES language spec itself say anything about fallback or error
> > mechanism for undefined constructor?
>
> > -Lofton.
>
>
> >>--
> >>  Benoit   mailto:benoit@itedo.com
> >>
> >>
> >> > Another item for the issues/errata queue.  Hmmm... Dave, do you know 
> how we
> >> > handle errata pages in OASIS?  (It's not like W3C, where the errata 
> page is
> >> > linked off of the cover page "Status" section with a persistent 
> URL.  But
> >> > Mary mentioned it once and I think there is something like a convention
> >> > with a fixed location/naming construct.)
> >>
> >> > -Lofton.




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