On Mar 22, 2006, at 20:25, Maciej Stachowiak wrote:

I'm not convinced that an exception is the best way to go, but being able to make the difference between the inability to process the request and the fact that nothing matched could prove important for versioning purposes. For instance say v2 supports the ability to return the first-letter inside an element while v1 doesn't, and I want to write code that tries to do that using selectors in such a way that if the implementation tells me it's impossible I fall back to some hand-coded munging.

If we can't differentiate we'll have to resort to hasFeature(). Quite frankly, give me exceptions any day over that :)