The slot specification (first argument) is either the slot-name, or the offset in the object (1-based). The latter possibility is for very specific (internal) use.

This method should only be used from a send-method that has the same name (selector) as the slot and serves as a wrapper around the slot to deal with side-effects:

:- pce_begin_class(person, object).

variable(date_of_birth,	date, get, "When person was born").
...

date_of_birth(Person, Date:date) :->
        (   send(Date, after, new(date))
        ->  send(Person, report, error,
                     'Cannot be born in the future!'),
                fail
        ;   send(Person, slot, date_of_birth, Date)
        ).

Bugs: This message should also apply to object-level defined attributes (see object->attribute.

See also

- class variable
- object<-slot
- class->send_method
- object->send_method