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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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