# The program demonstrates the general event handling pattern
# and some features of the EXT programming language.

# When releasing the case opening button,
# the relay 1 will be switched.

proc main()                             # the main routine (entry point)
{
    var e = $get_event_id();            # getting the event to handle
    if e == $EVT_INIT {                 # processing of the initialization 
        $set_event_mask($EM_SYSTEM);    # enabling the system events
    } else if e == $EVT_CASE_OPEN {     # processing of the case opening 
        toggle(1);                      # switching the relay 1
    }
}

proc toggle(n)                          # the output control routine
{                                       # n - output number
    var s = $get_output_state(n);       # getting the current state
    $set_output_state(n, !s);           # setting the inverse state
}