- From: T.V Raman <raman@google.com>
- Date: Tue, 27 Mar 2007 09:28:50 -0700
- To: dsr@w3.org
- Cc: raman@google.com, mikeschinkel@gmail.com, public-html@w3.org
Dave Raggett writes: > > On Mon, 26 Mar 2007, T.V Raman wrote: > > > Note that the XForms WG originally speculated on subsetting > > JavaScript, and for the reasons you mention decided to use XPath > > instead. > > Hi Raman, > > I am not sure what your point is in saying that. It was mostly a "historical" note --- to ensure that the background was not lost. > The only real > distinction is that XPath allows for the full set of XML > identifiers Actually the real distinction is being side-effect free. > which is larger than for ECMA 262, and that XForms was aligning > itself with the suite of XML specifications including XML The alignment with XML definitely made the XPath choice easier; however I believe we would have chosen ECMAScript if it weren't for the problem of side-effects. Another example of a W3C spec that debated long and hard about subsetting ECMAScript was the work on Semantic Interpretation in the VBWG. I tend to concurr with one of the sentiments expressed earlier on this thread; subsetting an existing language usually ends up inventing a new one. > Schema, XSLT, and XPath, so XPath was a clear winner over > ECMAScript. > Note that none of this is meant to take away from your goal of enabling the authoring of declarative constraints; I think the best way to motivate that is to keep spread-sheets in mind, and remember that we dont write a fresh program every time we file an expense report. > But for non-techies who don't know programming languages, but do > know simple arithmetic expressions from their school days, there are > therefore different criteria in play. > > As for the issues of calling external functions it doesn't matter > what expression language you use. Static analysis of > dependencies You're correct; external functions -- be it XPath or JavaScript -- are not any different from another when it comes to static analysis. > for function bodies is impractical. So you have to constrain such > functions. That is not a problem in practice, and if necessary you > can constrain the set of such functions to a predefined set. > > p.s. authoring tools could reversably translate between XPath and a > more user friendly format, so this isn't that big of a problem. > > Dave Raggett <dsr@w3.org> http://www.w3.org/People/Raggett -- Best Regards, --raman Title: Research Scientist Email: raman@google.com WWW: http://emacspeak.sf.net/raman/ Google: tv+raman GTalk: raman@google.com, tv.raman.tv@gmail.com PGP: http://emacspeak.sf.net/raman/raman-almaden.asc
Received on Tuesday, 27 March 2007 16:29:43 UTC