RE: [xsl] lookaheads in XSLT2 regexes

["Michael Kay" <mike@xxxxxxxxxxxx>]

> > That's not an acceptable definition for our purposes, so 
> it's arguably 
> > better to have no definition at all.
> 
> I don't know about acceptability, 

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)

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

I would imagine there would also be raised eyebrows about including "_" in
the set of "word" characters. That's something that only happens in geekdom.
But in the past the principle has been "if Perl defines it well, do what
Perl does, otherwise leave it out completely." 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.

Regards,

Michael Kay
http://www.saxonica.com/
http://twitter.com/michaelhkay