std::span in default bindings?

[NAThompson]

Currently, the list of all builtin conversions has a large number of extremely useful converters, however std::span has not yet been implemented.

Would it be sensible to add std::span? It appears to bind more naturally to numpy vectors than does std::vector and might be "the right way" to expose C++ memory to python in the future.

[Skylion007]

Would it be possible to have the std::span integration contained in its own header? If so, we could easily add it like we do for std::filesystem.

[NAThompson]

That would be more than acceptable for my use case; and I imagine would would well for everyone else.

[Skylion007]

We would gladly welcome a PR then.

[virtuald]

We use an LLVM backport of std::span, including conversions to/from buffer protocol objects. I don't want to make the PR myself, but happy for someone else to do it.

• Type caster: https://github.com/robotpy/robotpy-wpiutil/blob/main/wpiutil/src/type_casters/wpi_span_type_caster.h
• C++ portion of tests: https://github.com/robotpy/robotpy-wpiutil/blob/main/tests/cpp/wpiutil_test/module.cpp#L24
• Python portion of tests: https://github.com/robotpy/robotpy-wpiutil/blob/main/tests/test_span.py

[virtuald]

I did upgrade mine to std::span recently, still the same filenames.

Also, pybind11-abseil has a span implementation -- which also has a zero-copy conversion to/from buffer. Good reading material: https://github.com/pybind/pybind11_abseil/blob/master/pybind11_abseil/absl_casters.h#L317