Verify the readline stdlib module was compiled into Python

[jayvdb]

It is possible for the stdlib module readline to be missing if the GNU readline headers were not available with Python's 'configure' was run.

Thus this setup.py should fail a custom package is not being used and the stdlib module is not available.

[pombredanne]

@jayvdb Hey... do you want me to add you as co-owner on this repo?

[jayvdb]

@pombredanne , collaborator will likely be helpful. co-owner/pypi access not so helpful.

There is only a little bit to be done. I think the coala team can the patches in, and then we just need to do one release.

The goal is to remove the environment marker from
https://gitlab.com/coala/coala-utils/blob/master/requirements.txt , and not add more logic there.
Here seems like a more sensible location, as it already has some stuff in setup.py, and just needs it in the new wheel system.
cc @yzgyyang

[jayvdb]

While a 'configure' time failure would be good, it is probably not possible to combine this with #2 .

Another approach is to have an anyreadline module which provides a readline name which is the module for each system.

e.g.

from anyreadline import readline

Then that module can also include code to check that readline was compiled into Python on Linux, and give a sensible error if it is missing.

[jayvdb]

According to ludwigschwardt/python-gnureadline#52 , gnureadline may be a usable alternative on Linux and BSDs (and others) if the stdlib version wasnt built in.

So I believe we could (and should) add gnureadline as a dependency during setup.py, if the stdlib version wasnt built in.

Again, that isnt possible for a wheel to detect. As this is a very thin package, and we can do wheels for win32 and darwin, it is acceptable for this package to not have wheels for platforms where the "right" readline approach isnt known.

Another way to tackle this problem is to fix pyenv (and similar) to check if the OS readline lib & headers were installed and offer substitute headers before building a broken Python ;-)