Add PEP8 checks to automatic builds

[AartGoossens]

I made a start with this here: https://github.com/AartGoossens/sweatpy/tree/feature/isort_pylint
Any ideas on what to check are welcome (e.g. max line length).

[piotr-kubica]

Pep8 recommends up to 100 chars pro line.

For code maintained exclusively or primarily by a team that can reach agreement on this issue, it is okay to increase the nominal line length from 80 to 100 characters

Pylint complexity checker? https://pypi.python.org/pypi/pylint-mccabe

[AartGoossens]

Thanks @piotr-kubica.
Yes I agree that enforcing <100 is more reasonable today. (although I still tend to aim for <80 because I think it's still more readable)
I did not know about the McCabe complexity checker. To be honest I have not used a complexity checker like this in a development process before. How would you use it?

[piotr-kubica]

Sometimes the methods can become very long, introducing a lot of complexity and making it hard to test. The complexity checker would then give a hint for spotting such complex methods.
On start I would set the complexity (in pylint.conf) value low and see what happens. If it spots code that is fairly straightforward then I would increase the complexity number until it reaches a spot where we can say "ok it spots complex methods that are hard to understand and test and should be split into testable units".

[AartGoossens]

That sounds like a very useful thing to make part of the tests. I will include it in my PR.