[Python-Dev] Inheritance vs composition in backcompat (PEP521) (original) (raw)

Koos Zevenhoven k7hoven at gmail.com
Mon Oct 2 18:19:50 EDT 2017

On Oct 3, 2017 01:11, "Koos Zevenhoven" <k7hoven at gmail.com> wrote:

On Oct 3, 2017 01:00, "Guido van Rossum" <guido at python.org> wrote:

Mon, Oct 2, 2017 at 2:52 PM, Koos Zevenhoven <k7hoven at gmail.com> wrote

I don't mind this (or Nathaniel ;-) being academic. The backwards

incompatibility issue I've just described applies to any extension via composition, if the underlying type/protocol grows new members (like the CM protocol would have gained suspend and resume in PEP521).

Since you seem to have a good grasp on this issue, does PEP 550 suffer from the same problem? (Or PEP 555, for that matter? :-)

Neither has this particular issue, because they don't extend an existing protocol. If this thread has any significance, it will most likely be elsewhere.

That said, I did come across this thought while trying to find flaws in my own PEP ;)

-- Koos -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20171003/888ecf31/attachment.html>

More information about the Python-Dev mailing list