get-setf-expansion.lisp

(defun show-usage-of-get-setf-expansion (expr)
 (multiple-value-bind (temp-vars vals store-vars form access) (get-setf-expansion expr)
   (format t "vars=~S~%" temp-vars)
   (format t "forms=~S~%" vals)
   (format t "var=~S~%" store-vars)
   (format t "set=~S~%" form)
   (format t "access=~S~%" access)))

(show-usage-of-get-setf-expansion '(incf i))

;; prints:
;; vars=(#:I591 #:G592)
;; forms=(I (+ 1 I))
;; var=(#:NEW1)
;; set=(FUNCALL #'(SETF SETQ) #:NEW1 #:I591 #:G592)
;; access=(SETQ #:I591 #:G592)

(show-usage-of-get-setf-expansion '(incf i))

;; prints:
;; vars=(#:I593 #:G594)
;; forms=(I (+ 1 I))
;; var=(#:NEW1)
;; set=(FUNCALL #'(SETF SETQ) #:NEW1 #:I593 #:G594)
;; access=(SETQ #:I593 #:G594)

;; gensym #:NEW1 appears twice. bug?

environment:

$ uname -a
Linux DESKTOP-ORU04L0 4.4.0-17763-Microsoft #379-Microsoft Wed Mar 06 19:16:00 PST 2019 x86_64 x86_64 x86_64 GNU/Linux
$ ros run -- --version
SBCL 1.5.4