- From: Ian Hickson <ian@hixie.ch>
- Date: Tue, 30 Dec 2008 14:05:02 +0000 (UTC)
- To: Julian Reschke <julian.reschke@gmx.de>
- Cc: Larry Masinter <masinter@adobe.com>, "www-tag@w3.org" <www-tag@w3.org>
On Tue, 30 Dec 2008, Julian Reschke wrote: > > Does the spec specify how to parse or serialize a future element called > "foobar"? Yes. (The parsing algorithm might change in a future version, of course; that's the problem with a having a syntax that isn't self-descriptive, like XML, or forwards-compatible, like CSS. There's not much we can do about that.) > > > That's a very verbose way to state "must ignore unknown values". > > > > It's a precise way of saying it, that leaves nothing ambiguous. That's > > the whole point. > > I think the same precision can be reached with less verbosity. Oh, well, I'm sure it can be said more tersely, sure. (Just out of interest, how would you phrase it?) > > > So, if XML 1.0 *did* say that, how would you then introduce a new > > > value? Older recipients would ignore it, after all. > > > > If older recipients ignore the value, then we're golden. Just > > introduce the new value, and then you have predictable down-level > > behavior and predictable up-level behavior. > > Well, if it's ok for consumers to ignore a new value, then this is the > right approach. The problematic case is when that fallback behaviour is > not sufficient. Yes. That's where language design comes into play. But that is a mere detail of design compared to the broader issue, that specifications should define handling for all inputs and all conformance classes in detail and unambiguously. -- Ian Hickson U+1047E )\._.,--....,'``. fL http://ln.hixie.ch/ U+263A /, _.. \ _\ ;`._ ,. Things that are impossible just take longer. `._.-(,_..'--(,_..'`-.;.'
Received on Tuesday, 30 December 2008 14:05:58 UTC