Manual:DIL Manual/interrupt()

integer interrupt( flags : integer, dilexp, label )

   Set up interrupt matching message classes matching "flags",
   for example "SFB_COM" or "SFB_COM | SFB_MSG".

   When the program is activated on either of the specified conditions
   the 'dilexp' is evaluated. If true, then execution continues at 'label',
   otherwise the next interrupt is checked (if any).

   Interrupts are saved (restored), when 'recall' is set.
   Returns an integer which is used for clear() to clear an interrupt.

Example:

The following program shows, that the owner (self) of the program keeps
snoring while sleeping. The on_activation ensures that the program
is only activated when the owner is sleeping. However, since the interrupt
precede the on_activation, these may still be intercepted before the
on_activation. The on_activation is just another type of interrupt that
reacts on all flags (without actually setting them so that the program
is activated).

When the program receives the message "relief" the snoring stops briefly.
As used, "relief" may only be set once.

When the program receives the message "cured", the snoring stops completely
(i.e. the program quits itself).

 dilbegin

 var
    i : integer;

 code
 {
   /* Notice that the sequence in which the interrupts (and the on_activation)
     are executed, is quite important: You can be cured at *any* time. The
     program will skip if you are not sleeping. If you are sleeping you can
     be relieved. */

    interrupt(SFB_MSG, argument == "cured", the_end);

    on_activation(self.position != POSITION_SLEEPING, skip);

    i1 := interrupt(SFB_MSG, argument == "relief", relief);

    :loop:
    exec("snore", self);
    pause;
    goto loop;

    :relief:
    /* Suppose you can only be relieved once, then we must clear interrupt */
    clear(i1);
    pause;
    pause;
    goto loop;

    :the_end:
    /* Person is cured... */
    quit;
 }
 dilend

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