[Python-Dev] hierarchicial named groups extension to the re library

ottrey at py.redsoft.be ottrey at py.redsoft.be
Mon Apr 4 08:27:46 CEST 2005

Hi Gustavo!,

On 4/4/2005, "Gustavo Niemeyer" <gustavo at niemeyer.net> wrote:
>> Well, that would be something I'd want to discuss here.  As I'm not
>> sure if I actually ~want~ to match the API of the re module.
>If this feature is considered a good addition for the standard
>library, integrating it on re would be an interesting option.
>But given what you say above, I'm not sure if *you* want to
>make it a part of re itself.

After taking in the great comments made in this discussion, I'm now
thinking that it ~would~ be best to try and integrate the new
functionality with the existing re library (matching the current API),
as there is (at least some) re2 functionality that I think could fit
neatly into the existing re API.

As, like you say:
> This would avoid backward compatibility problems, would give each
> regular expression a single meaning, and would allow interleaving
> hierarchical/non-hierarchical groups.

>If we're going to introduce new features, we should try
>to do that without breaking the current well known meanings they


>I'm not in favor of that specific implementation.
>I'm open to discuss that further.

And I'm happy to work on a proposal that attempts to implement the new
functionality in a backwardly compatible, integrated way.

> I offer myself to integrate the change

Thanx!  That'd be great.

> once we decide on the right way to implement it,
> and achieve consensus on its adoption.

So I'll conclude from this discussion that (some implementation) of re2
is indeed worth adding to the re library (once we achieve consensus).

And as for creating a PEP...

>Josiah Carlson wrote:
>In general, if developers can readily agree that a functionality should
>be added (i.e. it is "obvious" for some reason), it is added right away.
>Otherwise, a PEP should be written, and reviewed by the community

I'd like to call the current functionality a "work in progress".
ie. I'd like to work on it more, taking on board the comments made here.

I'd also like to take this discussion off the python-dev list now and
shift it to pyre2.  (possibly to come back with a more polished proposal.)

We've set up a development wiki here:


(feel free to add any more suggestions.)

And there is also a mailing list, if anyone is interested and would like
to subscribe:




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