[Python-Dev] New regex module for 3.2?

[Tim Wintle]

On Mon, 2010-07-12 at 16:18 +0100, Michael Foord wrote: 
> On 12/07/2010 15:07, Nick Coghlan wrote:
> > On Mon, Jul 12, 2010 at 9:42 AM, Steven D'Aprano<steve at pearwood.info>  wrote:
> >
> > re2 deliberately omits some features for efficiency reasons, hence is
> > not even on the table as a possible replacement for the standard
> > library version. If someone is in a position where re2 can solve their
> > problems with the re module, they should also be in a position where
> > they can track it down for themselves.
> >
> 
> If it has *partial* compatibility, and big enough performance 
> improvements for common cases, it could perhaps be used where the regex 
> doesn't use unsupported features. This would have some extra cost in the 
> compile phase, but would mean Python could ship with two regex engines 
> but only one interface exposed to the programmer...

I'm not sure how common those cases are - I played around with RE2 a few
months ago and found that the majority of regular expressions in my own
code were noticeably slower running under RE2 than python's re module -
RE2 just puts much nicer theoretical bounds on cases that were (in my
code at least) unusual.

The really good use case for RE2 is for applications where users can
write regular expressions as input (exactly what RE2 was designed for) -
but I'm not sure how common those applications are.

Tim Wintle