— Associate a finalizer to an object.
Any lisp object.
A function or closure that takes one argument or
NIL no finalizer is
associated to the object. Otherwise
be a function or a closure of one argument, which will be invoked before the
object is destroyed.
Close a file associated to an object.
(defclass my-class () ((file :initarg :file :initform nil))) (defun finalize-my-class (x) (let ((s (slot-value x 'file))) (when s (format t "~%;;; Closing" s) (close s)))) (defmethod initialize-instance :around ((my-instance my-class) &rest args) (ext:set-finalizer my-instance #'finalize-my-class) (call-next-method)) (progn (make-instance 'my-class :file (open "~/.ecl.old" :direction :input)) nil) (si::gc t) (si::gc t) ;; Closing