Show how to auto-import plugin custom messages

[schaubh]

Summary

Document the required package initialization pattern for SDK plugins with custom messages.

Plugins that generate custom message bindings should import their generated messaging package before importing SWIG module wrappers:

from . import messaging
from . import myModule

This mirrors Basilisk’s own package-level messaging import and ensures custom Message<T> / Recorder<T> SWIG proxy classes are registered before users access module message fields.

Changes

• Updated the custom atmosphere plugin example to import custom_atm.messaging from custom_atm.__init__.
• Added documentation explaining why generated plugin messaging must be imported before module wrappers.
• Added a generated messaging/__init__.py docstring describing recorder proxy registration.
• Updated the example tests to use package-exposed generated messaging instead of explicitly importing message classes.

Testing

• git diff --check
• python3 -m py_compile examples/custom-atm-plugin/custom_atm/__init__.py examples/custom-atm-plugin/customExponentialAtmosphere/_UnitTest/test_customExponentialAtmosphere.py

pytest was not run locally because this environment does not have pytest installed.

[ReeceHumphreys]

Thanks for the fixes! In the future we probably want to update the cmake with a bsk_configure_package_init or something along those lines. Then users could just add this to their cmake:

bsk_configure_package_init(
  PACKAGE_DIR    "${PLUGIN_PKG_DIR}"
  SWIG_MODULES   customExponentialAtmosphere
)

I think this solution you have done is good for now though while we flesh out the SDK as it will unblock early adopters of it!

[schaubh]

Thanks for the feedback @ReeceHumphreys. The current solution does mimic what we are doing with BSK itself as well. So, at least we are consistent. If there is a better way to do this we can update both BSK and BSK-SDK.