Initial commit

Inspired by my own configuration and now distributed as a separate package.

persist-state.el

@@ -0,0 +1,72 @@
+;;; persist-state.el --- Persist variables regularly  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2023 Bram Schoenmakers
+
+;; Author: Bram Schoenmakers <me@bramschoenmokers.nl>
+;; Maintainer: Bram Schoenmakers <me@bramschoenmokers.nl>
+;; Created: 05 May 2023
+
+;; Package-Version: 0.1
+;; Keywords: convenience
+;; URL: https://apps.bram85.nl/git/bram/emacs-persist-state
+
+;; This file is not part of GNU Emacs.
+
+;;; Commentary:
+
+;;; Code:
+
+(defgroup persist-state nil
+  "Persist the Emacs state at regular intervals."
+  :group 'convenience)
+
+(defcustom persist-state-saving-functions nil
+  "A list of functions that should be executed as part of saving the state of the current Emacs function."
+  :type '(repeat function)
+  :group 'persist-state)
+
+(defvar persist-state--save-state-timer nil
+  "This variable holds the timer object to trigger regular saves.")
+
+(defcustom persist-state-save-interval
+  (* 15 60)
+  "Persist the Emacs state this amount of seconds."
+  :type '(integer)
+  :group 'persist-state)
+
+(defcustom persist-state-wait-idle
+  5
+  "When it's time to save, wait for this amount of idle time (in seconds)."
+  :type '(integer)
+  :group 'persist-state)
+
+(defun persist-state--regularly-run-on-idle (interval idle-seconds f &rest args)
+  "Run function F with ARGS every INTERVAL seconds, plus IDLE-SECONDS."
+  (run-with-timer interval interval
+                  (lambda ()
+                    (run-with-idle-timer idle-seconds nil
+                                         (lambda ()
+                                           (apply f args))))))
+
+(defun persist-state--save-state ()
+  "Save state but only when the user was active recently."
+  (when (< (float-time (current-idle-time)) persist-state-save-interval)
+    (mapc 'funcall persist-state-saving-functions)))
+
+;;;###autoload
+(defun persist-state-enable ()
+  "Start saving the Emacs state at the configured interval."
+  (setq persist-state--save-state-timer
+        (persist-state--regularly-run-on-idle persist-state-save-interval
+                                 persist-state-wait-idle
+                                 #'persist-state--save-state)))
+
+;;;###autoload
+(defun persist-state-disable ()
+  "Stop saving the Emacs state."
+  (when (timerp persist-state--save-state-timer)
+    (cancel-timer persist-state--save-state-timer)))
+
+(provide 'persist-state)
+
+;;; persist-state.el ends here