;;;
;;; Properties of interest:
;;;        $opens?     -        can this object be opened?
;;;        $open?      -        is it currently open?
;;;        $locks?     -        can this object be locked?
;;;        $locked?    -        is it currently locked?
;;;        $lit?       -        is it giving off light?
;;;        $transp?    -        is it transparent?
;;;        $weight     -        how much it weighs, in ounces.
;;;        $capacity   -        how much it can hold, in ounces.
;;;        $invisible  -        should the system describe this object? (see the
;;;                        obelisk in x.adv)
;;;

(property
    $parent
    $child
    $sibling
    $opens?
    $open?
    $locks?
    $locked?
    $lit?
    $transp?
    $weight
    initial-location
    $capacity
    $invisible?
    $SDESC
    $LDESC
    $EDESC
    $IDESC
    $visited?
    $onfloor?    )

(property
    north
    south
    east
    west
    northeast
    northwest
    southeast
    southwest
    up
    down)

(define (Parent   obj) (getp obj $parent  ))
(define (Child    obj) (getp obj $child   ))
(define (Sibling  obj) (getp obj $sibling ))
(define (Weight   obj) (getp obj $weight  ))
(define (Capacity obj) (getp obj $capacity))

(define (Set-Parent  obj p) (setp obj $parent  p))
(define (Set-Child   obj c) (setp obj $child   c))
(define (Set-Sibling obj s) (setp obj $sibling s))

(define (Locked? obj)            (getp obj $locked?))
(define (Locks? obj)             (getp obj $locks?))
(define (Open? obj)              (getp obj $open?))
(define (Opens? obj)             (getp obj $opens?))
(define (Lit? obj)               (getp obj $lit?))
(define (Transparent? obj)       (getp obj $transp?))
(define (Invisible? obj)         (getp obj $invisible?))

(define (Set-Open obj val)       (setp obj $open? val))
(define (Set-Locked obj val)     (setp obj $locked? val))

(define (SeeIn? obj) (or (Open? obj) (Transparent? obj)))