On Thu, Nov 19, 2020 at 5:16 AM Steve Holden <st...@holdenweb.com> wrote:
> On Wed, Nov 18, 2020 at 7:04 PM Daniel Moisset <dfmois...@gmail.com> > wrote: > >> [sorry for the duplicate, meant to reply-all] >> >> Thank you for this approach, I find it really helpful to put the >> conversation in these terms (semantics and guiding principles). >> >> It does help to rationalise discussion ;-) > >> [...] >> 4. "Objects should be able determine which patterns they match." >> This is something that you and I, and most of the authors of 622 agree >> on. What we found out when discussing this is that we didn't have clear >> what and how to open that customization. Some customization options added a >> lot of complexity at the cost of performance, some others were very simple >> but it wasn't clear that they would be actually useful, or extensible in >> the future. This has a lot to do with this being a somewhat new paradigm in >> Python, and our lack of knowledge on what the user community may do with it >> beyond what we imagined. So the decision was "pattern matching as it is >> presented without extensibility is useful, let's get this in, and once we >> see how it is used in the wild we'll understand better what kind of >> extensibility is valuable". For a crude analogy, imagine trying to get the >> descriptor protocol right when the basic python object model was being >> implemented. These things happened as different times as the use of the >> language evolved, and my opinion is that customization of the match >> protocol must follow a similar path. >> >> > I haven't so far understood whether the change proposed is intended to > start out in __future__. Given the preliminary nature of this development, > it would seem wise to retain the option to withdraw it or modify it > radically before production code depends on it. > The current proposal is not for it to be put behind a __future__ statement as it doesn't conflict with or break any pre-existing source code.
_______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/BN4HQBX72L5GMVNEBGQDOSF6F3L4VRTS/ Code of Conduct: http://python.org/psf/codeofconduct/
