AttributeError: module 'opengate_core' has no attribute 'GateMotionVolumeActor' — occurs at import time

[janikvhrubant]

I’m encountering an error immediately when importing opengate in a basic script. The full traceback is:

Traceback (most recent call last):
  File "z_qmc_simulation.py", line 1, in <module>
    import opengate as gate
  File ".../opengate/__init__.py", line 32, in <module>
    from .actor.helpers_actor import *
  File ".../opengate/actor/helpers_actor.py", line 12, in <module>
    from .MotionVolumeActor import *
  File ".../opengate/actor/MotionVolumeActor.py", line 5, in <module>
    class MotionVolumeActor(g4.GateMotionVolumeActor, gate.ActorBase):
                            ^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: module 'opengate_core' has no attribute 'GateMotionVolumeActor'

I verified that opengate_core is importable and inspected its contents:

python -c "import opengate_core; print(dir(opengate_core))"

This error occurs during the import process, specifically inside:

opengate/actor/helpers_actor.py
→ from .MotionVolumeActor import *
→ class MotionVolumeActor(g4.GateMotionVolumeActor, ...)

I inspected my opengate_core installation with:

python -c "import opengate_core; print(dir(opengate_core))"

The module contains many Gate...Actor classes (e.g. GateDoseActor, GatePhaseSpaceActor, etc.), but GateMotionVolumeActor is missing.

Environment:
• macOS (Apple Silicon)
• Python 3.11 in virtualenv (.venv11)
Questions:
1. Is GateMotionVolumeActor officially part of opengate_core?
2. If so, how can I enable its inclusion during build (e.g. via a CMake flag)?
3. If not, should MotionVolumeActor.py (and helpers_actor.py) be updated to handle its absence?

Let me know if you need my CMakeCache.txt, binding source, or build logs.

Thanks in advance for your help!

[dsarrut]

the MotionVolumeActor does not exist anymore. This concept has been replaced by dynamic parametrisation. Unfortunately, I cannot find the documentation about this concept (@nkrah ?), but you can find examples here :
https://github.com/OpenGATE/opengate/blob/master/opengate/tests/src/test030_dose_motion_dynamic_param.py

[nkrah]

@dsarrut : You are right. The documentation is still missing. I need to add it.

[nkrah]

@janikvhrubant : Please try to start from the test030 that @dsarrut shared with you, but do not hesitate to post any question!