Correct handling of case in unicode and regexps

[Devin Jeanpierre]

On Sat, Feb 23, 2013 at 12:41 PM, MRAB <python at mrabarnett.plus.com> wrote:
> Getting full case folding to work can be tricky. There's always going to
> be a limit to what's worth doing.
>
> There are also areas where it's not clear what the result should be.
> You've already mentioned matching 's' against 'ß' (fails) and matching
> 'ss' against 'ß' (succeeds), but how about matching '(s)(s)' against 'ß'
> (fails)?
>
> For the record, Perl also says that 'ss' matches 'ß', but 's+' does not.

I would find it helpful to know the exact rules. The regex module docs
say that it works, but don't say what it means to "work".

-- Devin