all, to find bugs in our Python code base a bit earlier, I looked into static type checking using mypy and I'd like to share my results. Mypy ( http://mypy-lang.org/ ) is a static type checker for Python that aims to combine the benefits of dynamic (or "duck") typing and static typing. As of now, running mypy on our code base already reveals some genuine bugs, especially with respect to Python 3 incompatibilities. Unfortunately, we will need to look into every module and message and manually separate bugs and false-positives. Here are two example errors: > pybind/mgr/restful/decorators.py:21: error: > Argument 1 to "split" of "bytes" has incompatible type "str"; expected "Optional[bytes]" This is an issue that will be fixed by https://github.com/ceph/ceph/pull/26712 > pybind/mgr/diskprediction_cloud/module.py:12: error: > Module 'string' has no attribute 'maketrans' which is already tracked as https://tracker.ceph.com/issues/38521 By adding additional type annotations to our Python code, we could enhance the quality of static type checking and thus reveal additional bugs. This is of course not mandatory! Here is the PR that adds a script that calls mypy: https://github.com/ceph/ceph/pull/26715 It also contains a list of messages printed by mypy. -- SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
