support exec, eval

[nschloe]

I took pybind11's eval.h plus tests and adapted it for nanobind. I had to remove eval_file as I couldn't find a stable-ABI equivalent for opening files (done with _Py_fopen_obj in pybind11).

@wjakob I believe this is ready for the review. The test failures seem unrelated.

[wjakob]

This looks like a great start! Here is some feedback on this first version.

[wjakob]

The CMake thing happens sometimes, unfortunately. Not sure what that is all about -- the next time you update the PR, it will likely succeed.

[wjakob]

This looks like it is close to mergeable. One remaining thing that is missing is basic Sphinx documentation that could likely be repurposed from pybind11.

[wjakob]

One last thing I remembered: besides copying the docs from nanobind, can you add the function signatures and document then added enum? This should go to docs/api_extra.rst, which documents opt-in parts of the nanobind API.

[nschloe]

I could actually make eval_file work as well. Let me try and have a look.

[nschloe]

Let's forget about that; I'm getting entangled in segfaults here. To be added as a later step. :)

[wjakob]

Ok. Ready for another review or potentially merge?

[wjakob]

Just a few minor remaining things I noticed.

[nschloe]

Ready for another review

Always ready! :) (Thanks for the good reviews.)

[wjakob]

Merged, thank you for your work!

[nschloe]

Thanks again for walking me through the process!

[nschloe]

[wjakob]

You'll have to be a lot more patient ;). There is a huge issue that I want to fix in an upcoming release (#307), and which requires some stabilization until then. If you cannot wait, just reference a particular commit of this repository (supported by pip, requirements.txt, etc.)