Stubs for zstd

[victorbnl]

zstd is an extension library written in C for Python. I'd like to add stub files for it. However, I don't know whether I should make a pull request on their repo or add them to typeshed.

I'd like to make a PR on their repo, the issue is I don't know how to provide stub files along with the module itself. I tried to add the stub files in the src/ directory, both as zstd.pyi and __init__.pyi, then I tried to add these files to the package_data section in the setup.py file. Nonetheless, the stubs seem to get ignored in all cases; testing on a project I have which depends on zstd, I keep getting:

error: Cannot find implementation or library stub for module named "zstd"  [import]

Is it even possible to ship those .pyi directly with the package? If so, how can I do so? Or should I just add them to typeshed anyway? Thanks!

[JelleZijlstra]

Sounds like you didn't add a py.typed file. See https://mypy.readthedocs.io/en/stable/installed_packages.html#creating-pep-561-compatible-packages for how to make an installed package compatible with mypy.

In general, we prefer if type information comes with the packages themselves, so the ideal would be for zstd itself to distribute stubs. If the zstd maintainers are unwilling to add types, however, typeshed would be happy to accept them.

[hauntsaninja]

Btw, https://github.com/indygreg/python-zstandard I think is a little better maintained and ships with a py.typed

[victorbnl]

Thanks for the suggestion, I'll consider using it then!

As for zstd, I added a py.typed file in added it in the package_data section, and it does get added, here is for proof the extracted wheel:

Still when I install it and run stubtest zstd I get MISSING

[JelleZijlstra]

I checked and zstd is distributed as a single .so file, which means it actually cannot be typed with a py.typed file; see python/typing#1333. The options are:

• Turn zstd into a package (as described in the typing issue)
• Wait for the typing issue to be resolved
• Put stubs in typeshed

[victorbnl]

As I don't know what's the developer's perspective regarding the issue and how the library is being used I wouldn't take the risk of turning it into an actual package, considering the unexpected side-effects it can have. I also don't want to wait for the issue to be fixed. I'll make the PR to add it to typeshed then. Thanks for the help!