Adding Extension Modules At Run-Time

Normally, PyOxidizer assembles all extension modules needed for a built application and the resources data embedded in the binary describes all extension modules.

The pyembed crate also supports providing additional extension modules, which are defined outside of PyOxidizer configuration files. This feature can be useful for Rust applications that want to provide extension modules through their own means and don’t want to use standard Python packaging tools (like or PyOxidizer config files for building them.

Statically Linked Extension Modules

You can inform the pyembed crate about the existence of additional Python extension modules which are statically linked into the binary.

To do this, you will need to populate the extra_extension_modules field of the PythonConfig Rust struct used to construct the Python interpreter. Simply add an entry defining the extension module’s import name and a pointer to its C initialization function (often named PyInit_<name>. e.g. if you are defining the extension module foo, the initialization function would be PyInit_foo by convention.

Please note that Python stores extension modules in a global variable. So instantiating multiple interpreters via the pyembed interfaces may result in duplicate entries or unwanted extension modules being exposed to the Python interpreter.

Dynamically Linked Extension Modules

If you have an extension module provided as a shared library (this is typically has Python extension modules work), it will be possible to load this extension module provided that the build configuration supports loading dynamically linked Python extension modules. See PythonExtensionModule Location Compatibility for more on this topic.

There is not yet an explicit Rust API for loading additional dynamically linked extension modules. It is theoretically possible to add an entry to the parsed embedded resources data structure. The path of least resistance is likely to enable the standard filesystem importer and put your shared library extension module somewhere on Python’s sys.path.