#+title: Emacs Persist State
#+author: Bram Schoenmakers

* Introduction

I don't leave Emacs often, but sometimes Emacs leaves me.

At moments like these, it's convenient to have a reasonably up to date state of recent files, bookmarks, history variables, etc. available when you restart Emacs again.

This package allows you to execute a function at a regular interval. To minimize any disturbance while you're working, a few seconds of idleness will trigger the execution of all save functions.

Supported packages:

#+begin_src elisp :exports results :results list
  (mapcar (lambda (package)
            (let ((label (or (plist-get (cdr package) :label)
                             (car package)))
                  (url (plist-get (cdr package) :url)))
              (if url
                  (format "[[%s][%s]]" url label)
                label)))
          persist-state-supported-packages-alist)
#+end_src

#+RESULTS:
- bookmark
- desktop
- Eshell history
- [[https://github.com/radian-software/prescient.el][Prescient.el]]
- recentf
- savehist

* Installation and usage

Clone the repository and put the package in your =load-path=.

#+begin_src elisp
  (use-package persist-state
    :ensure nil
    :load-path "lisp/persist-state"
    :init
    (persist-state-enable))
#+end_src

Then, add functions to =persist-state-functions= which should be executed, e.g. to save bookmarks at regular intervals:

#+begin_src elisp
  (add-to-list 'persist-state-functions #'bookmark-save)
#+end_src

* Configuration

This table shows which variables can be customized.

#+begin_src emacs-lisp :exports results :results table :colnames '("Custom variable" "Description")
  (let ((rows))
    (mapatoms
     (lambda (symbol)
       (when (and (string-match "^persist-state"
                                (symbol-name symbol))
                  (custom-variable-p symbol))
         (push `(,symbol
                 ,(car
                   (split-string
                    (or (get (indirect-variable symbol)
                             'variable-documentation)
                        (get symbol 'variable-documentation)
                        "")
                    "\n")))
               rows))))
    (sort rows (lambda (item1 item2)
                 (string< (car item1) (car item2)))))
#+end_src

#+RESULTS:
| Custom variable                | Description                                                             |
|--------------------------------+-------------------------------------------------------------------------|
| persist-state-save-interval    | Interval (in seconds) to persist state.                                 |
| persist-state-saving-functions | A list of functions that should be executed as part of saving state.    |
| persist-state-wait-idle        | When it's time to save, wait for this amount of idle time (in seconds). |

** COMMENT Attribution :noexport:

The code to generate the table of configuration items was inspired by an idea of [[https://xenodium.com/generating-elisp-org-docs/][Álvaro Ramírez]] (a.k.a. xenodium).

* License

MIT License

Copyright (c) 2023 Bram Schoenmakers

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.