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

[David Davis]

+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/631031e38270c5c7c2b2289ff4ab87a058447c5e/plugin/pulpcore/plugin/stages/content_unit_stages.py#L47-L59
> > [1]
> https://github.com/pulp/pulp/blob/631031e38270c5c7c2b2289ff4ab87a058447c5e/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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