[Python-Dev] Interested in serving on Steering Council

2019-01-02 Thread David Mertz
Hi Core Developers,

First thing: I am *not* a CPython committer.  I think most of you who are
will be somewhat familiar with me though.

Second: I was a Director of the PSF for a long while, and continue to chair
some Working Groups.  I've been mentioned in some PEPs.  I have written a
lot of articles and have given a lot of talks about Python, including about
recent or pending PEPs and similar matters.  I continue to work and train
around Python and open source (now with a focus on "data science", whatever
that is).

Third: I follow python-ideas and python-dev rather closely, and fairly
often contribute ideas to those lists.

Fourth: As I read PEP 8016, I cannot nominate myself to the Steering
Committee.  That seems good and proper to me.  But I believe I would be a
relevant and helpful member of the future Steering Committee if someone
wishes to nominate me and if the voters wish to elect me.

Thanks, David Mertz...

-- 
Keeping medicines from the bloodstreams of the sick; food
from the bellies of the hungry; books from the hands of the
uneducated; technology from the underdeveloped; and putting
advocates of freedom in prisons.  Intellectual property is
to the 21st century what the slave trade was to the 16th.
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Re: [Python-Dev] Interested in serving on Steering Council

2019-01-02 Thread Antoine Pitrou
On Wed, 2 Jan 2019 12:34:55 -0500
David Mertz  wrote:
> Hi Core Developers,
> 
> First thing: I am *not* a CPython committer.  I think most of you who are
> will be somewhat familiar with me though.
> 
> Second: I was a Director of the PSF for a long while, and continue to chair
> some Working Groups.  I've been mentioned in some PEPs.  I have written a
> lot of articles and have given a lot of talks about Python, including about
> recent or pending PEPs and similar matters.  I continue to work and train
> around Python and open source (now with a focus on "data science", whatever
> that is).
> 
> Third: I follow python-ideas and python-dev rather closely, and fairly
> often contribute ideas to those lists.
> 
> Fourth: As I read PEP 8016, I cannot nominate myself to the Steering
> Committee.  That seems good and proper to me.  But I believe I would be a
> relevant and helpful member of the future Steering Committee if someone
> wishes to nominate me and if the voters wish to elect me.

The primary question I would ask an external candidate is: how is it
that you never became a core developer (which implies some amount of
effort and dedication) but nevertheless would be willing to spend the
effort and dedication needed for serving on a Steering Council (*)?

(*) (or Committee, I don't remember :-))

Regards

Antoine.


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[Python-Dev] Return type of datetime subclasses added to timedelta

2019-01-02 Thread Paul Ganssle
Happy New Year everyone!

I would like to start a thread here for wider feedback on my proposal to
change the return type of the addition operation between a datetime
subclass and a timedelta. Currently, adding a timedelta to a subclass of
datetime /always/ returns a datetime rather than an instance of the
datetime subclass.

I have an open PR implementing this, PR #10902
, but I know it's a major
change so I did not want to move forward without more discussion. I
first brought this up on datetime-SIG

[1], and we decided to move the discussion over here because the people
most likely to object to the change would be on this list and not on
datetime-SIG.

In addition to the datetime-SIG thread, you may find a detailed
rationale for the change in bpo-35364
 [2],  and a rationale for
why we would want to (and arguably already /do/) support subclassing
datetime in bpo-32417  [3].

A short version of the strongest rationale for changing how this works
is that it is causing inconsistencies in how subclassing is handled in
alternate constructors of datetime. For a given subclass of datetime
(which I will call DateTimeSub), nearly all alternate constructors
already support subclasses correctly - DateTimeSub.fromtimestamp(x) will
return a DateTimeSub, for example. However, because DateTimeSub +
timedelta returns datetime, any alternate constructor implemented in
terms of timedelta additions will leak that implementation detail by
returning a datetime object instead of the subclass. The biggest problem
is that datetime.fromutc is defined in terms of timedelta addition, so
DateTimeSub.now() returns a DateTimeSub object, but
DateTimeSub.now(timezone.utc) returns a datetime object! This is one of
the most annoying things to work around when building a datetime
subclass, and I don't know of any situation where someone /wants/ their
subclass to be lost on addition with a timedelta.

From my understanding, this has been discussed before and the original
objection was that this implementation assumes that the datetime
subclass has a constructor with the same (or a sufficiently similar)
signature as datetime. This may be a legitimate gripe, but unfortunately
that ship has sailed long ago. All of datetime's alternate constructors
make this assumption. Any subclass that does not meet this requirement
must have worked around it long ago (or they don't care about alternate
constructors).

Thanks for your attention, I look forward to your replies.

Best,

Paul

[1]
https://mail.python.org/archives/list/datetime-...@python.org/thread/TGB3VZS5EKM4R2VFUA44323FZFRN2DSJ/

[2] https://bugs.python.org/issue35364#msg331065

[3] https://bugs.python.org/issue32417#msg331353




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