Supported Python and dependency versions

[rsyring]

I'd like to get a version support matrix defined and documented. Currently, tox is setup to run

• Python 2.6, 2.7, 3.3-3.6, pypy w/ Flask and SA at their latest released versions
• Some of those same versions w/ Flask 0.10 and SA 0.8

I would assume support for 2.6 and 3.3 should be able to be dropped considering tox won't even run those versions. See: #684

However, can we "officially" do that without a major point release? refs: #682

[davidism]

Drop Python 2.6 and 3.3, add 3.7, see Werkzeug for example. 3.4 ends in a few months. It's fine to drop versions in 2.4.

Should only need one env for lowest versions.

Flask <0.12 is not supported, but I don't think there's any reason not to allow it right now, although 3.0 should probably bump to Flask 1.0. Same with the min version of SQLAlchemy.

[rsyring]

#687 will take care of this for the 2.x branch

Leaving open and setting milestone to 3.0 so we remember to make updates for when 3.0 is released.

[hugovk]

Python 3.4 is EOL on Saturday (2019-03-16).

https://devguide.python.org/#status-of-python-branches

Here's the pip installs for Flask-SQLAlchemy from PyPI for February 2019:

category	percent	downloads
2.7	41.14%	393,179
3.6	35.89%	343,036
3.7	12.73%	121,637
3.5	8.06%	77,050
3.4	1.56%	14,910
null	0.53%	5,105
2.6	0.04%	424
3.3	0.02%	219
3.8	0.01%	99
3.2	0.00%	8
Total		955,667

Source: pypistats python_minor Flask-SQLAlchemy --last-month # pip install pypistats

[ticosax]

1st of January 2020, python2 will be officially unsupported.

We need to think how to phase it out. I'm in favour of dropping it as part of next major release as it will ease the maintenance burden of the project by not taking care of compatibility for older versions (supported python versions for flask-sqlalchemy >= 3.5)

[davidism]

Python 2 support can be dropped on January 1st, 2020, but not before then.

[rsyring]

I'm updating the support matrix to drop support for 3.4 for FSA 3.0+.

[davidism]

Dropped Python 2, 3.4, and 3.5 in #822 and #826.

[davidism]

SQLAlchemy 1.3 is only a year old, so I think it's ok to still support 1.2 minimum, it only requires one workaround in our code. I'll bump Flask minimum to 2.0 once that's released (it will come before FSQLA 3.0 is released), since that will match the Python >= 3.6 requirement.