Matlab fails to run Python built with Pybind

Attempting to call a member of a user-defined Python module which was built using Pybind. The module seems to import correctly via

mymodule = py.importlib.import_module("mymodule")

But on attempting to access a class from the module, I get this error:

>> myclass = mymodule.myclass

Cannot find class 'py.pybind11_builtins.pybind11_type'.

I've tested that the module loads and works correctly when accessed in Python. I'm using Matlab on Ubuntu, and Python 3.10

[Infinite_king]

Are you able to import and use functions in python modules from MATLAB ?

[Jay Castro]

Yes

[Grace Kepler]

This issue could be related to using custom C++ datatypes with pybind11 and currently may be a limitation for Python Interface.

[Sylwester Arabas]

For the record, this has also been reported on pybind11 issue tracker back in May 2022: https://github.com/pybind/pybind11/issues/3945 (where pybind11 maintainers suggested to report it to Matlab maintainers).

It's a big showstopper as there are more and more Python packages built using pybind11.

[Sylwester Arabas]

@Jay Castro, @Grace Kepler

Update: a workaround has just been proposed and succesfully tested here: https://github.com/pybind/cmake_example/pull/164

[David Truscott]

This is the work-around for that error that worked for me on Windows:

Create a file called 'pybind11_builtins.py' and place it in the folder where your python modules library resides. (For my Python 3.10 installation in Windows, it was {Path to Python Installation} \Lib folder.

The only line in that file should be 'pybind11_type=type' (without the apostrophes).

Reload your pyenv in Matlab,

>>py.importlib.import_module('pybind11_builtins')

>>py.importlib.import_module(' Your originally intended module here')