Let mode

Create emacs minor modes which set variables when activated and unset them when deactivated.

Usage

let-mode can be used to define a simple minor mode which temporarily sets a list of variables to some values when the mode is enabled and reverts them on disable.

For example here is a very simple local minor mode that sets up tabs for indentation in various major modes:

(defvar tabs-mode-revert-fn
  #'ignore
  "Variable to hold function to revert changes made by tabs-mode")

(define-minor-mode tabs-mode
  "Test case for let-mode"
  :global nil
  (if tabs-mode
      (setq-local tabs-mode-revert-fn
                  (let-mode-revertable-set-local
                   'indent-tabs-mode t
                   'tab-width 4
                   'c-basic-offset 4
                   'sgml-basic-offset 4
                   'js-indent-level 4
                   ;; etc.
                   ))
    ;; else
    (funcall tabs-mode-revert-fn)))

To instead create a global minor mode replace let-mode-revertable-set-local with let-mode-revertable-set and setq-local with setq.

Changelog

TODO