git clone 'git://github.com/skeeto/elisp-finalize.git'
This package provides finalizers for Emacs Lisp objects. Objects registered with this package will have a specified finalizer function run immediately after that object is garbage collected.
The API has one function:
finalize-register. It accepts an object, a
finalizer, and arguments to be passed to the finalizer. The object
being finalized will be unavailable to the finalizer.
This package works by taking advantage of weak references and
See also: Emacs Lisp Object Finalizers
delete-process as a finalizer to clean up a leftover process.
(require 'cl-lib) (require 'finalize) (cl-defstruct (pinger (:constructor pinger--create)) process host) (defun pinger-create (host) (let* ((process (start-process "pinger" nil "ping" host)) (object (pinger--create :process process :host host))) (finalize-register object #'delete-process process) object)) (setf pinger (pinger-create "localhost")) ;; => [cl-struct-pinger #<process pinger> "localhost"] (get-process "pinger") ;; => #<process pinger> ;; Allow object to be garbage collected. (setf pinger nil) (garbage-collect) ;; Process has been automatically cleaned up by the finalizer. (get-process "pinger") ;; => nil
Or using the
finalizable EIEIO mixin class, which calls
on a copy of the original object after garbage collection.
(require 'eieio) (require 'finalizable) (defclass pinger (finalizable) ((process :initarg :process :reader pinger-process) (host :initarg :host :reader pinger-host))) (defun pinger-create (host) (make-instance 'pinger :process (start-process "ping" nil "ping" host) :host host)) (defmethod finalize ((pinger pinger)) (delete-process (pinger-process pinger)))
Be mindful when using lexical scope and passing a lambda to
finalize-register. Uncompiled lambdas capture their entire
environment, which almost certainly
includes the object subject to finalization. This will
backfire and keep the object alive indefinitely. This situation will
only work correctly when your function is byte-compiled, which will
provide precise lexical environment capture.