time to drop python2 compatibility ?

[fchapoton]

in particular

• usage of imports from __future__ and from six (done)
• usage of xrange, iteritems and itervalues

Any opinion ?

Also:

• remove object inheritance in classes

[fchapoton]

also change cython language level to 3str or 3 ?

[NathanDunfield]

We officially dropped Python 2 support with the release of SnapPy 3.0; specifically, we only support Python 3.6 and newer. So removing all of that unused cruft would be great.

[fchapoton]

one little step in #56, will remove future in another pull request

[fchapoton]

See #67 for some details in this spirit

[fchapoton]

some care for (object) in #70

[fchapoton]

there probably remains some "try except" about imports that should be cleaned up.

And also code in pari.py about old sage versions that is obsolete

[NathanDunfield]

And also code in pari.py about old sage versions that is obsolete

Given that we don't support Python 2, any code for Sage < 8.9 can go. Also, on the plain-Python side, we now require cypari>=2.3 so the stuff referring to pre-2.2.0 can be deleted as well.

[fchapoton]

see #78

[fchapoton]

I have also found that

git grep "if sys.version" .
mac_osx_app/__boot__.py:if sys.version_info[0] == 2:
mac_osx_app/__boot__.py:    if sys.version_info[0] == 2:
mac_osx_app/dmg-maker/dmg-maker.py:if sys.version_info.major == 2:
mac_osx_app/setup.py:if sys.version_info >= (3,4):
opengl/CyOpenGL.pyx:if sys.version_info[0] < 3:
python/database.py:    if sys.version_info >= (3,4):
python/gui.py:if sys.version_info.major < 3 or sys.version_info.minor < 7:
setup.py:        if sys.version_info.major == 2:
setup.py:        elif sys.version_info == (3,4):

Can I go on and carefuly get rid of all that ?

[NathanDunfield]

Yes, please do.

[fchapoton]

Maybe one should close this issue. Remaining issues can be fixed when found.

[NathanDunfield]

Agreed, closing now.