fallback site.getsitepackages in virtualenv

[chapoton]

when run inside a virtualenv,

site has not attribute getsitepackages

This is a quick and dirty fallback in that case.

[chapoton]

New commits:

​8219d86	failback for site.getsitepackages in virtualenv
​3ca877f	more precise except clause

[embray]

That's annoying about virtualenv. I never ran into it before, I guess because using site.getsitepackages isn't very common. But it ought to work. I'm surprised it hasn't been fixed by now.

Unfortunately I think this workaround is incomplete, because if you're using a virtualenv with --system-site-packages this will still be incorrect. Maybe for Sage's purposes it doesn't matter though. I'd have to look at how SITE_PACKAGES is being used.

[fbissey]

Mostly SAGE_LIB is used except in src/sage/doctest/sources.py for no real good reason

sp = os.path.join(SAGE_LOCAL, 'lib', 'python', 'site-packages')

I replaced it by SAGE_LIB in sage-on-gentoo but never pushed it because it is bundled with a bunch of other stuff.

[chapoton]

I am trying to do from sage.all import * in an ipython3 session in a python3 virtualenv. This is the first failing point.

Then come problems with importing cython modules, but this is maybe another story.

[embray]

I've never seen any particular problem with importing Cython modules when using virtualenv...?

[chapoton]

I am probably doing something stupid. If you know the correct way to try importing sage in an ipython3 session, please tell me.

[embray]

Replying to chapoton:

I am probably doing something stupid. If you know the correct way to try importing sage in an ipython3 session, please tell me.

I don't know that it's you necessarily. The key words might be "importing sage". I haven't even tried using sage in a virtualenv, much less on Python 3. Normally there'd be nothing special to it.