Pybind11 to Nanobind

[petrasvestartas]

Nanobind is the next generation of pybind11.
The intent is to update compas_cgal wrapping method to nanobind.

How to run it?

Environment

Create or use an environment with compas, compas_viewer and numpy

Build It

To build a project run:
pip install -e .
or verbose:
pip install -e . -v

First time this command runs, it downloads the C++ source code of CGAL, Eigen and Boost.
Any other time you run this command again, only build process is executed.

Run example

compas_cgal/tests/test_meshing_remesh.py

Goal of the pull request

This pull request intends to implement nanobind for:
a) faster C++ compilation times when precompiled headers are used
b) dependency download when pip install -e . is called (no conda dependencies)
c) use CGAL with Boost and get rid of GMP and MPFR dependencies

ToDo:

☑2025-02-27 nanobind hello world works and cgal, boost and eigen is downloaded on the first call of "pip install -e ."
☑2025-02-28 reference headers and wrap one single method
☑2025-02-05 setup precompiled headers for faster development time
☑2025-02-07 Part 1 wrap the rest of current compas_cgal methods
☑ 2025-02-08 Part 2 wrap the rest of current compas_cgal methods
2025-02-10 Documentation.
2025-02-11 test the repository on MAC M and Intel Chips as well as Linux
2025-02-12 Github CI
2025-02-13 discuss the distribution to pypi and conda

[petrasvestartas]

I would like to ask a review of the current stage of the code.
Currently, there is only one method that is closely aligned how pybind11 was written in a nanobind style.

After review and changes, the goal is to implement the rest of the methods.

[tomvanmele]

so far so good it seems. just a few questions/suggestions:

• what is the plan with the remaining files of the repo?
• why is compas.h/cpp renamed to stdafx.h/cpp?
• i find the "manual profiling" in the tests a bit messy. perhaps the tests can just be about testing, while separate dedicated scripts are used for profiling (ideally with a profiler)

[petrasvestartas]

Plan for the Remaining Repository Files

Source Files

• The plan is to migrate all C++ and Python files from the current repository and translate them one by one to Nanobind, keeping the differences as minimal as possible.

Binaries for Linux, Mac, and Windows

• We can either build the binaries ourselves and push them to PyPI or test whether Conda can handle this (though I have no experience with Conda). I saw nanobind conda recipes, there should be a way.

GitHub Actions

• They probably will need to be updated according to current changes.

Contribution Guide

• Contribution guide has to be updated too.

Why Was compas.h/cpp Renamed to stdafx.h/cpp?

• I will rename stdafx.h back to compas.h. But it has to be one header file, for this reason all the methods use inline keyword.
• compas.h will serve as the main header and should ideally be compiled once as a precompiled header:
  Creating precompiled header files
• scikit-build, that is used by nanobind, helps to connect CMake C compilation with pip installation of Python. I am trying to figure out how to set precompiled headers to speed up the building process for development.

Manual Profiling in Tests

I find the "manual profiling" in the tests a bit messy. Perhaps the tests should focus solely on testing, while separate, dedicated scripts handle profiling (ideally using a profiler).

• I will clean up the test files.

[petrasvestartas]

Precompiled headers are working!

After setting this locally:

   pip install nanobind scikit-build-core[pyproject]
   conda install cmake
   pip install --no-build-isolation -ve .
   pip install --no-build-isolation -ve . -Ceditable.rebuild=true

Build time without precompiled headers:

Build time with precompiled headers:

For precompiled headers, it is always good to place as many 3rd party headers to one single file as possible so that C/C++ code changes in other files would not take too much time to wait.

[tomvanmele]

i think you need a blank line before the start of a list

[petrasvestartas]

Updated, all examples were missing this.

[tomvanmele]

please put the workflows back so we can start running tests on push again

[petrasvestartas]

Ok, let's see what is happening on ubuntu.

[tomvanmele]

please remove the "if name is main" guards from the examples. they serve no purpose...

[tomvanmele]

Cool!