How to implement an actor#

Mandatory basic class structure#

  1. Implement an initialize() method which should at least:

    • call the initialize() method from the python super class;

    • call the InitializeCpp() method from the C++ super class;

    • call the InitializeUserInfo() method from the C++ super class;

    • If you need to perform specific checks, e.g. plausibility of user input parameters, you will probably want to do that before calling the C++ methods.

    • Example:
      def initialize(self):
    ActorBase.initialize(self)
    # possibly implement some checks here ...
    self.InitializeUserInfo(self.user_info)
    self.InitializeCpp()

  2. Implement a __initcpp__() method. This should at least call the C++ constructor method and add actions if needed. Example:

    def __initcpp__(self):
    g4.GateSimulationStatisticsActor.__init__(self, self.user_info)
    self.AddActions({"StartSimulationAction", "EndSimulationAction"})

    Do not call the C++ constructor in the python __init__() method. This will cause problems when a simulation is run in a subprocess. Reason: The subprocessing mechanism relies on de-/serialization and GATE expects a __initcpp__() method to make sure the C++ constructor is called after deserialization (see __setstate__() in actors/base.py).

  3. Inherit first from the python base class and then from the C++ base class. In other words, write:

    class SimulationStatisticsActor(ActorBase, g4.GateSimulationStatisticsActor):
    # docstring, IDE hints, methods, etc.

    Do not write:

    class SimulationStatisticsActor( g4.GateSimulationStatisticsActor, ActorBase):
    # docstring, IDE hints, methods, etc.

  4. Refer to the super class explicitly and do not use the super() builtin from python because it cannot resolve C++ super classes.