[plt-scheme] equal? operator

On Nov 22, Hans Oesterholt-Dijkema wrote:
> 
> > So, what I will do, is indead take your advice and try to create a 
> > weak hash table holding
> > all the proos variables currently active in memory.
> >
> I implemented this:
> 
> (define PROOS-STORE (make-hash-table 'equal 'weak))
> 
> (define (proos-store->list)
>   (hash-table-map PROOS-STORE
>           (lambda (key val)
>             (list key val))))
> 
> (define (pobject-from-oid oid _class)
>   (let ((class (proos-class _class)))
>     (if (eq? class #f)
>     (error (string-append "proos class definition for " _class " not 
> found"))
>     (let* ((obj (hash-table-get PROOS-STORE (list oid) (lambda () #f))))
>       (oodb-dbg "PROOS-STORE: " oid obj)
>       (if (eq? obj #f)
>           (let ((obj (class 'from-oid oid)))
>         (hash-table-put! PROOS-STORE (list oid) (make-weak-box obj))
>         (oodb-dbg "PROOS-STORE: " oid obj)
>         obj)
>           (weak-box-value obj))))))
> 
> oid's are 32<oid<64bit integers. I noticed a normal hash table 
> (make-hash-table 'weak)
> will not find my oids (they're to big). Now I resorted to (list oid) for 
> the key in the hash
> table *and* an 'equal property on the hash tables. But can It be done 
> safely without the
> (list ...)?

Yes -- because `equal?' works fine on bigints.  Also -- why to you
make weak boxes?  -- The hash table stores values weakly anyay...

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!