What does a run-to-completion step consist of?

What does a run-to-completion step consist of?

• A. The exit behavior of the source state, the transition's effect, and the entry behavior of the target state
• B. Only the transition's effect
• C. The entry behavior of the target state and the exit behavior of the source state
• D. The guard condition only

Answer: (A)

A run-to-completion step is the atomic sequence that occurs when a transition fires: the exit behavior of the source state runs first, then the transition’s effect is executed, and finally the entry behavior of the target state runs. This order ensures a clean state change from old to new, with the destination initialized before any further events are processed. The guard condition is checked before the transition fires and is not part of this step, so it doesn’t count among the actions that happen in a run-to-completion step. The described sequence includes all three parts—exit, transition action, and entry—which is why it’s the best answer.

A run-to-completion step is the atomic sequence that occurs when a transition fires: the exit behavior of the source state runs first, then the transition’s effect is executed, and finally the entry behavior of the target state runs. This order ensures a clean state change from old to new, with the destination initialized before any further events are processed. The guard condition is checked before the transition fires and is not part of this step, so it doesn’t count among the actions that happen in a run-to-completion step. The described sequence includes all three parts—exit, transition action, and entry—which is why it’s the best answer.