prf-theme

A simple theme switcher for Emacs.

Was made originally to work with now legacy color-theme (Emacs pre-24) and got updated to support deftheme.

It's certainly not the best implementation there is. For (potentially) better alternatives, have a look at the Similar Projects section at the end of this document.

Installation

Not on Melpa.

For now, the recommended way to install is with use-package, quelpa and quelpa-use-package.

(use-package prf-theme
  :quelpa (prf-theme :fetcher github :repo "p3r7/prf-theme"))

Configuration

Configure var prf/theme/theme-list with the list of themes you want to cycle through.

The the can also be updated at run time and would start back at the fiest theme in this case.

Then call (prf/theme/initialize) to activate the first theme in your list.

To cycle bewteen themes, call prf/theme/cycle-theme. For conveniece, you can bind it to a key.

If you load helm, addtionnal command helm-prf-theme-choose will let you select the theme to switch to from the list.

Sample config

;; NB: use defer to prevent theme to get applied at init time
(use-package chocolate-theme
  :defer t)
(use-package white-sand-theme
  :defer t)

(use-package prf-theme
  :quelpa (prf-theme :fetcher github :repo "p3r7/prf-theme")
  :demand

  :bind ([f12] . prf/theme/cycle-theme)

  :init
  (setq prf/theme/theme-list '(chocolate white-sand))

  :config
  (prf/theme/initialize))

(use-package helm-prf-theme
  :after (prf-theme helm)
  :ensure nil

  :bind (("C-<f12>" . helm-prf-theme-choose)))

Implementation details

Cycling

The implementation is the most straightforward way to do it.

A copy of configured prf/theme/theme-list is created: prf/theme/current-theme-list.

We cycle through it by popping out the first element (the car) and setting it as the current theme.

Once prf/theme/current-theme-list is empty, the cycle back by re-setting it to the value of prf/theme/theme-list.

Unloading / Loading theme

For deftheme, we have first to disable-theme the previous one to then load-theme the next. Otherwise faces from previous theme would be kept.

Legacy color-theme represent themes as functions. To load one we'd need to just funcall it. There is no need to unload the previous theme.

deftheme / color-theme abstraction

Abstraction of the theme implementation is achieved by defining function aliases.

(if (>= emacs-major-version 24)
    (progn
      (defalias 'prf/theme/apply-theme #'prf/deftheme/apply-theme)
      (defalias 'prf/theme/revert-theme #'prf/deftheme/revert-theme))
  (defalias 'prf/theme/apply-theme #'prf/color-theme/apply-theme)
  (defalias 'prf/theme/revert-theme #'prf/color-theme/revert-theme)
  (require 'color-theme)
  (with-eval-after-load "color-theme"
    (color-theme-initialize))
  (setq color-theme-is-global     t
        color-theme-is-cumulative t))

Similar projects

• https://github.com/myTerminal/theme-looper
• Commands doremi-color-themes+ and doremi-custom-themes+ from DoReMi
• Spacemacs' spacemacs/cycle-spacemacs-theme in its core theme support