[SciPy-Dev] dropping python 2.7 and numpy <1.13.3

[Pauli Virtanen]

Hi,

la, 2018-11-10 kello 19:22 -0800, Ralf Gommers kirjoitti:
> I've always had in mind that SciPy would follow NumPy in its timeline
> for dropping Python 2.7. However, as far as I can tell we've never
> had the discussion on this list. So here's the proposal:
> Let's follow NumPy's timeline [1], which says that from 1 Jan 2019
> onwards new releases will be Python 3 only, and the last release
> before that date will be an LTS release. That means SciPy 1.2.0 will
> be the LTS release, and 1.3.0 will be >= py3.5.

Following Numpy on the Py3 plan sounds good to me.

On the cleaning up thing, it may indeed be best to avoid unnecessarily
removing the Py2 workarounds, as the more the LTS branch diverges, the
more work is required in backporting things to it. New code of course
can follow Py3 only.

> Also, we haven't changed the minimum numpy version we support in quite a
> while, we're still at 1.8.2. And that will have to change anyway after
> dropping Python 2.7. The current minimum numpy versions we require are:
> - py27: 1.8.2
> - py35: 1.9.3
> - py36: 1.12.1
> - py37: 1.13.1
> We have always aimed to support at least 4 numpy versions (i.e. 2 year old
> versions). The differences per Python version in minimum numpy version are
> annoying (we don't consistently check that in our main __init__.py or in
> setup.py even), so I propose that for SciPy 1.3.0 we raise the minimum
> required NumPy version to 1.13.3. That'll still be 4 supported releases,
> 1.13.3-1.16.x.

That's probably fine, 1.13.3 is from 2017. Situations where you are
able to upgrade Scipy but not Numpy are also somewhat rare, so this
seems a low-risk decision.

	Pauli