[Python-Dev] Requesting pronouncement on PEP 463: Exception-catching expressions

[Victor Stinner]

Hi,

2014-03-12 18:09 GMT+01:00 Guido van Rossum <guido at python.org>:
> I want to reject this PEP. (...)
> this was a well-written and well-researched PEP, and I think you've done a
> great job moderating the discussion, collecting objections, reviewing
> alternatives, and everything else that is required to turn a heated debate
> into a PEP. Well done Chris (and everyone who helped), and good luck with
> your next PEP!

I spend many weeks to work (write the PEP *and* implement them) on the
following PEPs and Guido rejected them:

- PEP 416: Add a frozendict builtin type
- PEP 410: Use decimal.Decimal type for timestamps

It's hard to accept that a wonderful idea at a first look is not a
good idea. Some months later, I now agree and see issues of my PEPs.
The PEP process ensures that the Python "language" (+ stdlib) keeps
consistent and well designed.

Even if a PEP is rejected, it becomes the best reference if someone
requests the same or a similar feature some months or years later.
Rejected PEPs explain almost how the Python language was designed.

For thanks Chris, and I hope that it's not too hard for you to accept
the fact that your "inline try/except" idea is maybe not as good as
you expected :-)

Victor