Re: rotatef mystery

Ken Tilton <kennytilton@xxxxxxxxxxxxx> writes:

Saw this in the doc for rotatef, don't get it:

"If a place produces more values than there are store variables, the
extra values are ignored. If a place produces fewer values than there
are store variables, the missing values are set to nil. "

OK: (rotatef x y z)

How does a place, say, y produce more values than there are store
variables?!

kt


(defparameter *a* 1)
(defparameter *b* 1)
(defparameter *c* 1)

(defun fun () (values *a* *b* *c*))
(defun (setf fun) (val)
(setf *a* val
*b* (* val val)
*c* (* val val val))
(values *a* *b* *c*))

(define-symbol-macro y (fun))

Have fun!

(I don't know how y will behave in rotatef, no time now to find out).

--
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Relevant Pages

  • rotatef mystery
    ... Saw this in the doc for rotatef, ... If a place produces fewer values than there are store variables, the missing values are set to nil. ... "We are what we pretend to be." ... -Kurt Vonnegut ...
    (comp.lang.lisp)
  • Re: rotatef mystery
    ... Ken Tilton wrote: ... If a place produces fewer values than there are store variables, the missing values are set to nil. ... Closer to MOP & ContextL: http://common-lisp.net/project/closer/ ...
    (comp.lang.lisp)