guideline

Consider using an exception handler for a rendezvous within the main loop inside each task.

In the following example, an exception raised using the primary sensor is used to change Mode to Degraded still allowing execution of the system:

...
loop

   Recognize_Degraded_Mode:
      begin

         case Mode is
            when Primary =>
               select
                  Current_Position_Primary.Request_New_Coordinates (X, Y);
               or
                  delay 0.25;
                  -- Decide whether to switch modes;
               end select;

            when Degraded =>

               Current_Position_Backup.Request_New_Coordinates (X, Y);

         end case;

         ...
      exception
         when Tasking_Error | Program_Error =>
            Mode := Degraded;
      end Recognize_Degraded_Mode;

end loop;
...

rationale

Allowing a task to terminate might not support the requirements of the system. Without an exception handler for the rendezvous within the main task loop, the functions of the task might not be performed.

notes