Re: [xsl] lookaheads in XSLT2 regexes

[Michael Ludwig <milu71@xxxxxx>]

Michael Kay schrieb am 02.03.2010 um 09:21:10 (-0000):
> 
> There are two aspects of a definition that would make it unacceptable
> to the WGs:
> 
> (a) any definition that is context-sensitive (so that instance
> documents become valid or invalid against a schema depending on who is
> validating them - if the sender of a document tests it for validity,
> they want it to be valid to the recipient as well)

There could be a facility to set the context in the schema. In Perl,
there are certain operations that change the context that determines
which semantics are applied, like bytes or characters. Of course, that
doesn't make it easier to understand.

> (b) any definition that is deeply coupled to assumptions about the
> orthography of European languages.

Could you give an example of such coupling? Isn't that handled by the
Unicode standard? Not that I know much about it ...

> In my view we've already copied too many of Perl's mistakes, like the
> strange rules on recognizing whether \12 is a back-reference to group
> 12 or a back-reference to group 1 followed by a digit 2.

I don't even know about that rule. It's clear that users don't have to
care about such details to the extent that implementors do.

Thanks for taking the time to explain!
-- 
Michael Ludwig