[cells-devel] A question about the use of vectors in CELLS

[Kenneth Tilton]

Frank Goenninger wrote:
> It just occurred to me that a simple :unchanged-if function should do 
> the trick, no ?

That is always my first reaction, too. Two problems: Cells works off 
(setf slot-value) if you will, and no code goes through that on (setf 
aref). The second problem is almost the same. Even this sequence:

    (setf (aref (myvector self) 42) 'hi-mom)
    (setf (myvector self) (myvector self)) ;; to get to unchanged-if

...would not work because Cells saves the slot-value for comparison and 
in this case before and after are the same vector -- so the old element 
42 of course now holds 'hi-mom.

kt