add support for enums

[evanfwelch]

marshmallow_enum is part of the marshmallow ecosystem. Accordingly, as a primary user of dataclasses, I would love marshmallow_dataclass to support enums. This PR adds that functionality as well as the requisite doctests.

[evanfwelch]

hmm this could be a mistaken addition to pipfile, will remove

[lovasoa]

In fact, enums are already supported, but only in the marshmallow3 branch (published as a pre-release to pypi). I did not backport the feature, because I thought marshmallow 3 was going to be released soon, and we could merge it into master. Unfortunately, marshmallow 3 has been a pre-release for several months, and it looks like it won't be released anytime soon.

So enum support is very welcome, but it should be a backport of how it is done in the marshmallow3 branch. Or even better, we may have a single branch (and a single release) that works with both marshmallow 2 and 3. Working with the two in parallel induces a lot of duplicated efforts and confusion.

[evanfwelch]

Hey @lovasoa that makes sense, I'm sorry I missed the support in the marshmallow 3 branch. I too have been waiting for marshmallow 3.x for quite some time and when it gets released a lot of my problems will go away. I will take a peek at your marshmallow 3 branch and see if I have any ideas on how to backport or write it once for both versions. Thanks

[evanfwelch]

Have a look now, I think this is what you had in mind

[lovasoa]

Yep, it's perfect ! You can merge master (and especially 23ce55b) into your branch, and we'll be ready to merge. Don't forget to add marshmallow_enum to the extra_requires in setup.py.

[evanfwelch]

Thanks for the code review, I will update this branch with those changes (I like the extra_requires approach too).

[lovasoa]

It's marges; thank you again @evanfwelch !