Best practice for inserting a non-physical directory on an import path?

[jwnimmer-tri]

For my concrete use case, see the BCR packaging of nanobind's stubgen library at bazelbuild/bazel-central-registry#10007 specifically the overlay/BUILD.bazel file.

The https://pypi.org/project/nanobind/ PyPI package provides from nanobind.stubgen import StubGen as the canonical import spelling. The documentation says the same.

However, the upstream file layout in git is just src/stubgen.py, without nanobind as a concrete directory name.

What's the best / preferred way to write a BUILD file for this particular source file layout, so that src/stubgen.py is importable as from nanobind.stubgen import ...?

In cc_library there is include_prefix to tack on extra directories to the front of the #include path. I don't see anything similar in py_library. I though I'd seen this requested as a feature in the past, but I can't seem to find that ticket anymore.

My solution so far is to create a shim file import/nanobind/stubgen.py that uses importlib.util to manually load the module and then re-export everything.

Other solutions involving symlinks or copying files seemed less portable.

[mohammadrezwankhan]

[jwnimmer-tri]

A question about best practices necessitates a human response from ecosystem expert(s). If I wanted to know what an AI agent thought about my question, I would have just asked the AI myself (and I already did that before posting the question).

[rickeylev]

What i'd recommend is generating a file at the desired location and passing it as input to py_library. e.g.

py_library(
  name = "nanobind",
  srcs = ["nanobind/stubgen.py"],
  imports = "."
)
genrule(
  name = "gen",
  srcs = ["stubgen.py"],
  outs = ["nanobind/stubgen.py"],
  cmd = "cp $(SRCS) $(OUTS)"
)

A custom rule can be used to create a symlink using actions.symlink

Other solutions involving symlinks or copying files seemed less portable.

How so? That's essentially what a py_library.include_prefix type thing would do. Generate a symlink at the desired location that points to the original location, then set the imports attribute information.