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Is it possible to configure emacs so it uses different theme for tramp buffers than for defaults? Say, I use twilight by default, but while editing sth via ssh I'd like to switch to pastels-on-dark...

Changing colors are great at providing a feeling that ”something is different”…

This question in fact covers a few problems:

a) whether there is any natural way to use per-buffer theme (I failed to find one)

b) if not, what is the best way to hook emacs so it switches theme depending on the current buffer (so far I have preliminary solution I am not happy with, see below)

c) and, specifically, how to adapt that to tramp case

Note: I found load-theme-buffer-local. For some reason it does not work for me (once I call it on some buffer, the same theme remains active for every other buffer too).

Here is a partial solution for b) case I found some-time ago. I am not happy with it (it fires only when I open new file and does not react to buffer switch, it fails to revert to default in some cases, and it works only for per-dir-tree case), but maybe it could be improved:

;; in .emacs

(defvar my-local-theme nil 
   "Name of current theme (intended to be overriden where necessary)")

(defun my-set-local-theme ()
   "If variable mkylocal-theme is set, loads this theme."
   (interactive)
   (when (bound-and-true-p my-local-theme)
       (unless(member my-local-theme custom-enabled-themes)
       (message "Setting local theme to %s on %s" my-local-theme (current-buffer))
       (load-theme my-local-theme t))))

(add-hook 'hack-local-variables-hook 'my-set-local-theme)

;; In .dir-locals.el on top of some source tree

(
  (nil
    (my-local-theme . twilight-anti-bright)
  ))

For completeness: I also use the following trick to load themes cleanly, so the code above does not unload themes.

(add-hook 'after-init-hook
      (lambda nil
        (defadvice load-theme 
          (before theme-dont-propagate activate)
          (mapcar #'disable-theme custom-enabled-themes))))
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2 Answers 2

Reset to default
4

I don't know how to enable/disable custom-themes for a buffer only. The following works for changing the global custom-theme when you enter a Tramp buffer, or when you leave it.

(add-hook
  'buffer-list-update-hook
  (lambda ()
    (if (and (not (window-minibuffer-p))
        (file-remote-p default-directory))
       (enable-theme 'pastels-on-dark)
     (disable-theme 'pastels-on-dark))))
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4
  • It is interesting and goes into the right direction. Still I have some mysterious problem here (likely interaction with some module(s) I use - mahaps projectile, ido, or flex-ido): whenever I open tramp file, emacs starts to flicker, and either keeps doing that, or leaves empty window). Once I Ctrl-G this state, and later C-x b to remote buffer, it has proper theme. Still, flickering happens to reappear also in other cases (like C-x 1 which removed remote window...)
    – Mekk
    Mar 2, 2015 at 7:48
  • (my first instinct is to replace not window-minibuffer-p with some "positive" requirement, checking that it is true editor buffer; also, mayhaps some variable checking whether thing is in progress just now). WIll give it a try. (thank you very much for pointing buffer-list-update-hook, this is crucial thing here...)
    – Mekk
    Mar 2, 2015 at 7:49
  • It turned out I had to work a bit more until I get more-or-less satisfactory effect, but this suggestion put me on the proper track, so thank you and I accept your answer as the solution.
    – Mekk
    Mar 2, 2015 at 22:56
  • This buffer-list-update-hook fired all the time for me. default-directory also didn't play well with tab-bar.
    – HappyFace
    Mar 24, 2021 at 10:19
2

I tried to develop Michael's suggestion, the result turned out to be a few pages of code, so I versioned it: https://bitbucket.org/Mekk/emacs_libs-theme-switcher/

Any suggestions how to improve this code are welcome.

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4
  • 3
    These days I've pushed tramp-theme to GNU ELPA. It uses another approach, using face-remapping-alist. You might try it if still interested in.
    – Michael Albinus
    Feb 19, 2016 at 8:55
  • This repo is down.
    – HappyFace
    Mar 24, 2021 at 10:33
  • @MichaelAlbinus How do I set different themes in tramp-theme-face-remapping-alist? It seems to ask for details such as the background color, while I just want to use a predefined theme.
    – HappyFace
    Mar 24, 2021 at 10:34
  • Hmm, this looks rather like a feature request (but I haven't thought about in detail). Pls contact us via the [email protected] ML; I fear, SX is not well suited for this kind of analysis.
    – Michael Albinus
    Mar 24, 2021 at 12:17

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