Use Matlab with not supported Py3.x version (e.g. ML 2021a with Py 3.9)?

I would like to use Matlab 2021a with py3.9. Unfortunately there 2021a only supports py 3.7 and 3.8. Is there any possibilty to enable ml 2021a to work with py 3.9?

Answer 1

[Walter Roberson]

Yes, of course there is a possibility.

Python is open source code. You can get a copy of the 3.9 code and alter the numbering and recompile it, and install your customized version.

How well it will work...

[Henning]

Ok, this requires modifications on the py-side. Unforunately the py-installation is given an can not be changed. Is there a possibility to enable ML to work with py 3.9, i.e. by applying modifications on the ML side?

[Walter Roberson]

Perhaps. For example if you wrote your own version of pyenv() that lied about which version of python was installed, then perhaps it would be able to execute.

[Henning]

Do you have any idea how this is been done? The file pyenv.m contains only a description, no code inside. I have not idea how to approach that problem.

[Walter Roberson]

pyenv is built-in code, so you would have to figure out what it is supposed to do, and write your own version of it. You would place your version earlier on the path than the Mathworks version: files earlier on the path are used intead of files later on the path (generally speaking.)

pe = pyenv

pe = 
  PythonEnvironment with properties:

          Version: "2.7"
       Executable: "/usr/bin/python"
          Library: "libpython2.7.so.1.0"
             Home: "/usr"
           Status: NotLoaded
    ExecutionMode: InProcess

It might be a bit tricky to create an object of the right class

which -all pyenv

built-in (/MATLAB/toolbox/matlab/external/interfaces/python/pyenv)

!find /MATLAB/toolbox/matlab -name \*PythonEnvironment\* -print

/MATLAB/toolbox/matlab/external/interfaces/python/+matlab/+pyclient/@PythonEnvironment
/MATLAB/toolbox/matlab/external/interfaces/python/+matlab/+pyclient/PythonEnvironment.m

[Walter Roberson]

It looks like possibly it uses

toolbox/matlab/external/interfaces/python/+python/+internal/pyinfo.m

which tells the python executable to run pyinfo.py to return information about the execution environment.

If that is what is getting invoked internally, then overriding it will take a bit of work. Earlier I said "generally speaking", but when that + folder structure is used and the internal code uses dot separated names like python.internal.pyinfo('C:\Python33\python.exe'), then that overrides the path for the most part... you would need to replace the entire python class to override an internal execution of python.internal.pyinfo (unless you executed the pyinfo.py into something that lied for you.)