After a lot of research, I did not find any proper way to stop callbacks from being called from a state that has already been transitioned.

For example imagine two states:

• "GO_FORWARD": Tells the robot to go forward until the front LIDAR measures distance less than 2m from the front wall.
• "STOP": The robot stops.

The "scan" callback in the GOFORWARD state takes the values of the front LIDAR. However, even when the state machine transitions from GOFORWARD to STOP, the scan callback is still active.

The only walk-around solution I found so far to this is to have a boolean flag in an if statement at the beginning of the callback, that turns False when the condition of the 2m is met.

Is there a way to properly terminate a state (and all its callbacks), when the state machine shifts to another state?