define-modify-macro

define-modify-macro is a Lisp macro in `cl.el'.

(define-modify-macro NAME ARGLIST FUNC &optional DOC)

Define a `setf'-like modify macro.
If NAME is called, it combines its PLACE argument with the other
arguments from ARGLIST using FUNC. For example:

(define-modify-macro incf (&optional (n 1)) +)

You can replace this macro with `gv-letplace'.