I've been playing with the idea of being able to build a module/extension in Rust that plugs in to RustPython, and I think I've come up with a pretty decent way of doing it. I've drawn some inspiration/learned about Rust dynamic loading from this ffi guide.

• Add libloading as a dependency.
• Add a field to VirtualMachine that's a Vec of libloading::Librarys.
• In the module resolution process, check if there's a *.so or *.dll on the PYTHONPATH, maybe have a specific prefix or suffix to designate that it's specifically a RustPython extension.
• Load that library and store it in the Vec<Library>, and then load a fn from there with a name like rustpython_init_module and a signature along the lines of

  type ExtensionInitFn = unsafe extern fn(vm: &mut VirtualMachine);

• Call that ExtensionInitFn.

I think it's pretty straightforward, but does anyone have any ideas for the parts that could be filled in, e.g. resolution along the PYTHONPATH?