[Pulp-dev] Proposal to drop support of Python 3.5 for Pulp 3

[Tatiana Tereshchenko]

Big +1

Tanya

On Wed, Sep 12, 2018 at 4:50 PM, David Davis <daviddavis at redhat.com> wrote:

> +1
>
> David
>
>
> On Tue, Sep 11, 2018 at 10:35 AM Jeff Ortel <jortel at redhat.com> wrote:
>
>> +1
>>
>> On 09/07/2018 01:09 AM, Simon Baatz wrote:
>> > I had a discussion on IRC with Brian yesterday which led to the
>> > question whether we can drop support for Python 3.5. I think there are
>> > good reasons for this, see the rationale below.
>> >
>> > Brian proposed to initiate a vote on this topic (and find out whether
>> > this "community thing" works :-) ).
>> >
>> > Please send feedback by Friday Sept 14th. Especially, let me know if
>> > there are specific reasons for depending on Python 3.5. The
>> > corresponding issue is 3984 [7].
>> >
>> > Cheers,
>> > Simon
>> >
>> >
>> > Rationale:
>> >
>> > The trigger for the discussion was to get rid of boilerplate code like
>> > this [0], [1] to handle batches in the stages API. This becomes a
>> > single line [2] when using an asynchronous generator [3]. Adding the
>> > `batches()` async generator to Pulp core would simplify existing
>> > stages and ease implementation of stages in plugins.
>> >
>> > Async generators have been introduced in Python 3.6. Thus, to make the
>> > `batches` generator available in the Pulp core plugin API, we either
>> >
>> > - have to drop support for Python 3.5 or
>> >
>> > - reimplement the async generator as an async iterator (which would be
>> >    more convoluted but looks doable)
>> >
>> >
>> > I prefer to drop 3.5, since this will allow to use additional language
>> > features[4]. Among them:
>> >
>> > - As said, async generators/async comprehensions. Async generators are
>> >    simpler to write and understand than async iterators.
>> >
>> > - String interpolation "f-Strings" [5]
>> >
>> > - dict objects preserve insertion-order (officially declared part of
>> >    the language with Python 3.7). Eliminates a source of subtle
>> >    "works on 3.6, sometimes works on 3.5" bugs.
>> >
>> > - One version less to support is always a good thing (provided nobody
>> >    really requires it)
>> >
>> > - Type annotations are currently not used by the Pulp project, but if
>> >    the project decides to use them in the future: IMHO type annotations
>> >    (which are great btw.) began to feel “right† with 3.6. Working
>> with
>> >    them in 3.5 can be clumsy at times.
>> >
>> > - And of course: [6]
>> >
>> >
>> > Python 3.6 has the OS/distribution support we need:
>> >
>> > - Python 3.6 SCL is available for RHEL 7 / CentOS 7
>> > - It is part of Fedora as of Fedora 26
>> >
>> > For Ubuntu, it is part of 18.04 LTS. Debian does not have Python 3.6 in
>> stable yet.
>> >
>> >
>> >
>> > [0] https://github.com/pulp/pulp/blob/631031e38270c5c7c2b2289ff4ab87
>> a058447c5e/plugin/pulpcore/plugin/stages/content_unit_stages.py#L47-L59
>> > [1] https://github.com/pulp/pulp/blob/631031e38270c5c7c2b2289ff4ab87
>> a058447c5e/plugin/pulpcore/plugin/stages/artifact_stages.py#L48-L60
>> > [2] https://github.com/gmbnomis/pulp_cookbook/blob/
>> ca4882cecab16995c5713d27131da8112a5f5a0c/pulp_cookbook/app/
>> tasks/synchronizing.py#L98
>> > [3] https://github.com/gmbnomis/pulp_cookbook/blob/
>> d44ed593925b78c046e1b568810b15acbdad5ac4/pulp_cookbook/app/
>> tasks/synchronizing.py#L26
>> > [4] https://docs.python.org/3/whatsnew/3.6.html
>> > [5] https://docs.python.org/3/whatsnew/3.6.html#pep-498-
>> formatted-string-literals
>> > [6] https://twitter.com/raymondh/status/844955415259463681
>> > [7] https://pulp.plan.io/issues/3984
>> >
>> > _______________________________________________
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>> > Pulp-dev at redhat.com
>> > https://www.redhat.com/mailman/listinfo/pulp-dev
>>
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