PEP 484 type annotations for Twine

[ygingras]

Update 4/25/2020: See #231 (comment) below for the current roadmap to completion.

I am considering adding type annotations to Twine to help my team do static analysis of code that depends on it. Would a pull request containing type annotations be merge back?

More info on type annotations:
PEP 484: https://www.python.org/dev/peps/pep-0484/
mypy, the type-checker of choice these days: http://mypy-lang.org/

Given the need to support Python 2.x, the preferred format for annotations would be as Type Comments, but I would be open to do .pyi stubs if that makes it easier for everyone.

Please provide guidance and requirements and I will take it from there.

[sigmavirus24]

@ygingras Where to .pyi stubs tend to live? Would it be acceptable to store them in a separate directory from the source, e.g., _stubs?

[ygingras]

Ian, the stubs can be anywhere and a _stubs dir would be perfect for them, indeed.

[sigmavirus24]

Let's do that then. =) I've been interested in them for a while, and this wouldn't be a bad project to experiment with them.

[sigmavirus24]

Hey @ygingras how has this been going?

[brainwane]

Tim Abbott of Zulip has written up a guide to adding static type annotations to a pre-existing codebase that folks might find helpful if they want to start working on adding these annotations to twine:

how mypy works, the benefits and pain points we’ve seen in using mypy, and share a detailed guide for adopting mypy in a large production codebase (including how to find and fix dozens of issues in a large project in the first few days of using mypy!).

[ygingras]

Hi everyone. It was probably obvious from my radio silence, but I have move on to different projects and I won't be doing this work myself. I still think the annotations would be useful, but since this was mostly an idea to scratch one of my itches, I think we can safely close this issue unless someone else is particularly excited about this work.

[brainwane]

@waseem18 would you be interested in working on this with me? It's a bit of a big project but it takes place in several steps and over several PRs I think we could make progress.

[waseem18]

I would absolutely love to work on this @brainwane
I'll start going through the Zulip content, Project documentation and PEP 484.

[fhocutt]

A handful of us at PyCon are interested in working on this. @sigmavirus24 @waseem18 did you have strong preferences for using stub files instead of python2-compatible annotations in the code itself? Personally I prefer not having to switch between files to get the type information but can go with the stubs.

[sigmavirus24]

@fhocutt I would prefer that they be in separate stub files. I would also prefer them to live along side the files they're annotating. I think @waseem18 has started working on that