The 'onSignal' callback

Event number: 43
Generated for: System and APL (child task) objects

The onSignal callback allows Parent and Child tasks to send messages to each other, with associated data. It is invoked in an APL object belonging to a parent task when the child task executes the Signal method of its System object. Conversely, it is invoked in the System object of a child task when the Parent executes the Signal method of its APL child task object.

During the callback, ⎕WARG contains the data (which can be any APL array or overlay) which the calling task passed as the argument to the Signal method.

The event-specific parameters in ⎕EV are (in index origin 1):

        ⎕EV[6]         Task ID for the task which sent the signal

See the section on APLX Multi-tasking for more details.