Wrong python in Sage shell?

[Simon King]

Hi!

The following happens with a Py-3 build of Sage: I open a sage-shell,
and then I get
(sage-sh) king@klap:src$ sage --python --version
Python 3.7.3
(sage-sh) king@klap:src$ python --version
Python 2.7.15

Is it expected that the default python version in a py-3 install is a
py-2?

Best regards,
Simon

[Dima Pasechnik]

is  this python2 from your OS, or from Sage's installation?

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[Vincent Delecroix]

It is sort of normal. [PEP0394] used to say that python
should be an alias for python2. But now it says that it
should either be python2 or python3.

Sage just follows the logic that was in place.

[PEP0394] https://www.python.org/dev/peps/pep-0394/

Vincent

[Simon King]

Hi Dima,

On 2019-08-29, Dima Pasechnik <dim...@gmail.com> wrote:
> is this python2 from your OS, or from Sage's installation?

From Sage's installation (apparently Sage-with-py-3 also builds
python-2):

(sage-sh) king@klap:~$ which python
/home/king/Sage/git/py3/local/bin/python
(sage-sh) king@klap:~$ which python3
/home/king/Sage/git/py3/local/bin/python3

Best regards,
Simon

[Frédéric Chapoton]

Hello

Somebody (else) should make sure that every single remaining piece of python2 is removed from a python3 sage. In particular, we should not build python2 at all.

Frédéric

[Samuel Lelievre]

Possibly somewhat related (sorry if not): after building Sage

for Python 3, running `sage -t` lets the doctesting framework

decide what to set `optional` to, and apparently it uses

"python2" rather than "python3"; is this the desired behaviour?

$ ./sage --python --version

Python 3.7.3

$ ./sage -t --all -p 2

Running doctests with ID 2019-08-29-17-56-03-a7156513.

Git branch: develop

Using --optional=build,dochtml,python2,sage

[Jeroen Demeyer]

On Thu, Aug 29, 2019 at 6:02 PM Samuel Lelievre
<samuel....@gmail.com> wrote:
> Possibly somewhat related (sorry if not): after building Sage
> for Python 3, running `sage -t` lets the doctesting framework
> decide what to set `optional` to, and apparently it uses
> "python2" rather than "python3"; is this the desired behaviour?

Yes, "python2" is installed as optional package and this is simply
running tests for that optional package. There aren't any such tests,
but the test framework doesn't a priori know that.

"python3" is not optional, therefore it's not listed in the --optional options.

I agree that it's confusing, but it's not a bug.

[John H Palmieri]

On Thursday, August 29, 2019 at 7:15:51 AM UTC-7, Frédéric Chapoton wrote:

Hello

Somebody (else) should make sure that every single remaining piece of python2 is removed from a python3 sage. In particular, we should not build python2 at all.

See https://trac.sagemath.org/ticket/28426