> On May 7, 2020, at 1:56 PM, Craig Rodrigues <rodr...@crodrigues.org> wrote: > > > > On Wed, Apr 22, 2020 at 12:28 AM Glyph <gl...@twistedmatrix.com > <mailto:gl...@twistedmatrix.com>> wrote: > > >> On Apr 21, 2020, at 8:57 PM, Craig Rodrigues <rodr...@crodrigues.org >> <mailto:rodr...@crodrigues.org>> wrote: >> >> Does anyone else have opinions on >> type hints and mypy? > > We use them at work, and on some other Twisted projects (Klein) and they're > absolutely awesome. Even with type comments, mypy is a huge upgrade to how > one writes and maintains Python; with annotations, it's a major upgrade to > the language. > > The first step here, however, is to set up the CI infrastructure (tox, etc) > to run mypy so that we can ensure that as we start writing type hints, we > don't accidentally get any of them wrong and back ourselves into any corners. > Mypy can catch a surprising number of bugs with just the implicit > type-checking it does on values that come from the standard library. In > fact, if we do `mypy src/twisted` right now, and exclude the things that > would be fixed by adding in https://github.com/Shoobx/mypy-zope > <https://github.com/Shoobx/mypy-zope> ("method must have at least one > argument" zope.interface definition errors) and fixing up some simple type > hints (has no attribute "skip") we still have almost a thousand type errors > that we should figure out a way to start correcting or systematically > skipping if they're false positives. I guarantee you there's at least one > real bug in there though. > > As you know, I tend to be pretty cautious about sweeping changes to the code > that might make it harder to maintain on older versions - type hints are an > exception where I think it's absolutely worthwhile to go All In early on. > But CI infrastructure for this stuff is a must-have and it might be tricky to > get set up initially. > > > > Earlier this week, I merged to trunk a new tox rule for running mypy with > mypy-zope. You can use it by > running the following command in the top-level Twisted directory: > > tox -e mypy > > mypy reports a lot of errors, but I think we can take several passes through > the Twisted codebase to clean those up. > > Once we clean up the errors, we can integrate the tox rule with Travis or > Azure CI or CircleCI (whatever works best). > > I submitted a few PR's to start cleaning up these errors: > https://github.com/twisted/twisted/pull/1264 > <https://github.com/twisted/twisted/pull/1264> (has no attribute "skip") > https://github.com/twisted/twisted/pull/1261 > <https://github.com/twisted/twisted/pull/1261> (Too few arguments to > "makeTestCaseClasses")
Thank you for doing this work, Craig! I strongly suspect that mypy is going to spot more than a few real bugs in our codebase, and I can think of at least one enthusiastic user (me) who wants Twisted to start shipping stubs for our users to use! This also reminded me to file https://twistedmatrix.com/trac/ticket/9816#ticket <https://twistedmatrix.com/trac/ticket/9816#ticket> because i couldn't find it filed already. -glyph
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