with :cpp:func:`simgrid::s4u::Engine::register_actor` or
with :cpp:func:`simgrid::s4u::Engine::register_function`.
- If you are stuck with MSG, use :cpp:func:`MSG_process_create`,
- :cpp:func:`MSG_process_create_with_arguments` or
- :cpp:func:`MSG_process_create_with_environment`.
-
:``start_time``: Useful to delay the start of your actor.
-1 starts the actor immediately.