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

[Kenneth Tilton]

Kenneth Tilton wrote:
> 
> 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.

er, because it is not "old", it is the same as in EQ vector.

kt