Upgrade to cypari2

[saraedum]

No description provided.

[saraedum]

I would like to package this for conda-forge. However, cypari is not on conda-forge but cypari2 is which is probably better anyway…

[saraedum]

cypari vendors pari it seems. So some changes are needed to make the CI happy again.

If you are in general fine with this, I can try to fix the CI.

[videlec]

cypari2 is not an upgrade of cypari but a fork. The main reason why cypari still exists is because

• it supports Windows (now, cypari2 should also thanks to cysignals #63)
• it provides binary wheels which package all together: gmp, cysignals, pari and the Python interface (see cypari2 #19). This simplifies the installation procedure for users (that do not have a distribution).

[saraedum]

Thanks for the clarification. So, what about making realalg work with cypari & cypari2, whichever is available?

[videlec]

I think this would be reasonable (especially if people are using SageMath which is bundled with cypari2). However it will be delicate to make the setup.py script of realalg to handle the dependencies correctly. How do you specify alternative dependencies?

[saraedum]

I don't think this can be done. The sane approach seems to not have an explicit dependency in setup.py but throw an exception if neither is installed that tells you what you should do.

[videlec]

Much less user friendly than an explicit dependency...

[saraedum]

I don't disagree but unfortunately setup.py has no hooks to do something like this. The other option is to split this into two pypi packages with different dependencies but I don't think that this is very helpful either.

[videlec]

@MarkCBell Because of #3 it would be nice to allow both cypari or cypari2.

(BTW, I expect https://github.com/flatsurf/pyeantic (mostly written in C) to be much faster...)

[videlec]

In azure and appveyor Python 3.5, 3.6 and 3.7 we got

py35 run-test: commands[0] | py.test --hypothesis-profile=ci --duration=20 --junitxml=results.xml
ERROR: usage: py.test [options] [file_or_dir] [file_or_dir] [...]
py.test: error: unrecognized arguments: --duration=20
  inifile: /home/vsts/work/1/s/tox.ini
  rootdir: /home/vsts/work/1/s

ERROR: InvocationError for command /home/vsts/work/1/s/.tox/py35/bin/py.test --hypothesis-profile=ci --duration=20 --junitxml=results.xml (exited with code 4)

[videlec]

The test failure has nothing to do with @saraedum branch, see #4

[saraedum]

@MarkCBell @videlec tests pass now.

[videlec]

See also the related MarkCBell/flipper#3

[videlec]

Independently of the installation procedure, this try/except in the code is an improvement!

[MarkCBell]

Sorry for the delay but I think I finally have a solution for this. I've now written a number of interfaces to backends that use cypari, cypari2 and sympy. This means that the only required dependency is now sympy. So if used on its own then realalg will fall back on its sympy implementation which is good enough to allow users to run basic examples (slowly). However if it can import cypari or cypari2 then it will use these, allowing larger more complex examples to be done.

The latest version of realalg (0.2.2) has this functionality. Let me know what you think.

[videlec]

Very good! Thanks.

You can definitely close this merge request.