After installing via ELPA, I can add the following code to my .emacs.

(eval-after-load "theme-changer" '(change-theme 'solarized-light 'solarized-dark))

But the code is not run on start-up; I have to manually load the file theme-changer.el or theme-changer.elc, and then the code will be run. Therefore, the package is not automatically loaded when installed via ELPA, which is a problem.

I'm getting this error on startup (from solar.el it seems):

Debugger entered--Lisp error: (wrong-type-argument arrayp nil)
  solar-exact-local-noon((10 29 2013))
  solar-sunrise-sunset((10 29 2013))
  sunrise-sunset-times((10 29 2013))
  change-theme(solarized-light zenburn)
  eval-buffer(#<buffer  *load*-516236> nil "/Volumes/Data/uri/.emacs.d/config/_appearance.el" nil t)  ; Reading at buffer position 156
  load-with-code-conversion("/Volumes/Data/uri/.emacs.d/config/_appearance.el" "/Volumes/Data/uri/.emacs.d/config/_appearance.el" nil t)
  require(_appearance)
  eval-buffer(#<buffer  *load*> nil "/Volumes/Data/uri/.emacs.d/init.el" nil t)  ; Reading at buffer position 273
  load-with-code-conversion("/Volumes/Data/uri/.emacs.d/init.el" "/Volumes/Data/uri/.emacs.d/init.el" t t)
  load("/Volumes/Data/uri/.emacs.d/init" t t)
  #[0 "^H\205\262^@     \306=\203^Q^@\307^H\310Q\202;^@ \311=\204^^^@\307^H\312Q\202;^@\313\307\314\315#\203*^@\316\202;^@\313\307\314\317#\203:^@\320\nB^R\321\202;^@\316\322^S\323$
  command-line()
  normal-top-level()

I've managed though to eval it once or twice from a buffer, w/o a problem, and it worked fine, so not sure where the problem is.

I've got is setup like this:

(setq calendar-location-name "Geneva, Switzerland")
(setq calendar-latitude 46.12)
(setq calendar-longitude 6.9)
...
(require 'theme-changer)
(change-theme 'solarized-light 'zenburn)

Though I've tried different combos of themes and locations...

I really like this package. I have been using theme-changer on emacs 26 to switch themes automatically.

But after upgrading to emacs 27, the theme cannot be switched automatically, and the theme can be set correctly only at startup.

% emacs --version
GNU Emacs 24.3.1

I'm an Emacs newbie and I'm having problems with your plugin. I installed it via ELPA, then added this to my init.el:

(setq calendar-location-name "Dallas, TX") 
(setq calendar-latitude 32.85)
(setq calendar-longitude -96.85)

(change-theme 'adwaita 'wombat)

And when I launch Emacs, I get this.

Warning (initialization): An error occurred while loading `/home/curacao/.emacs.d/init.el':

Symbol's function definition is void: change-theme

To ensure normal operation, you should investigate and remove the
cause of the error in your initialization file.  Start Emacs with
the `--debug-init' option to view a complete error backtrace.

This is the backtrace from Emacs launch with --debug-init flag.

Debugger entered--Lisp error: (void-function change-theme)
  (change-theme (quote adwaita) (quote wombat))
  eval-buffer(#<buffer  *load*> nil "/home/curacao/.emacs.d/init.el" nil t)  ; Reading at buffer position 719
  load-with-code-conversion("/home/curacao/.emacs.d/init.el" "/home/curacao/.emacs.d/init.el" t t)
  load("/home/curacao/.emacs.d/init" t t)

Both M-x load-theme <RET> wombat and M-x load-theme <RET> adwaita work fine.

First of all thank you for writing and maintaining this project. I use it everyday.

Not sure how useful this will be generally but I would like the theme to change at one hour before sunset rather than exactly at sunset because it starts to get pretty dark at that point. I would appreciate allowing to set an offset for this.

If this is something worth pursuing, I can try implementing this if you can give me some pointers on how to get started. I have never worked on emacs plugins before but I am willing to try.

Thank you again.

I have the following code in my .emacs:

    ;; use a light theme during the day and a dark one for the night
    (progn
      (setq calendar-location-name "Belo Horizonte, Brazil"
            calendar-latitude -19.919
            calendar-longitude -43.938)
      (require 'theme-changer)
      (change-theme 'solarized-light 'solarized-dark))

But when I start Emacs, for example at night, it do not change to the dark theme. If I evaluate manually works.

Debugger entered--Lisp error: (void-function first)
first((4 18 2023))
theme-changer-hour-fraction-to-time((4 18 2023) 6.1333333337679505)
theme-changer-sunrise-sunset-times((4 18 2023))
change-theme(leuven leuven-dark)
load-with-code-conversion("c:/.emacs.d/generalX1.el" "c:/.emacs.d/generalX1.el" nil t)
require(generalX1 "/.emacs.d/generalX1.el")
load-with-code-conversion("c:/Users/Admin/.emacs.d/init.el" "c:/Users/Admin/.emacs.d/init.el" t t)
load("c:/Users/Admin/.emacs.d/init" noerror nomessage)
startup--load-user-init-file(#f(compiled-function () #<bytecode 0x270a9e9b83ab4e8>) #f(compiled-function () #<bytecode -0x1f3c686ddc0da035>) t)
command-line()
normal-top-level()

After run the following code, I got wrong-type-argument number-or-marker-p nil

(setq calendar-location-name "Dallas, TX") 
(setq calendar-latitude 32.85)
(setq calendar-longitude -96.85)
(require 'theme-changer)
(change-theme 'solarized-light 'solarized-dark)

backtrace:

Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)
  cl-truncate(nil)
  (let* ((now (decode-time (current-time))) (month (first date)) (day (car (cdr date))) (year (car (cdr (cdr date)))) (zone (ninth now)) (frac-hour (cl-truncate hour-fraction)) (hour (first frac-hour)) (frac-minutes (cl-truncate (* (car (cdr frac-hour)) 60))) (minute (first frac-minutes)) (frac-seconds (cl-truncate (* (car (cdr frac-minutes)) 60))) (sec (first frac-seconds))) (encode-time sec minute hour day month year zone))
  theme-changer-hour-fraction-to-time((2 3 2020) nil)
  (let* ((l (solar-sunrise-sunset date)) (sunrise-time (theme-changer-hour-fraction-to-time date (car (car l)))) (sunset-time (theme-changer-hour-fraction-to-time date (car (car (cdr l)))))) (list sunrise-time sunset-time))
  theme-changer-sunrise-sunset-times((2 3 2020))
  (first (theme-changer-sunrise-sunset-times (theme-changer-tomorrow)))
  (let* ((now (current-time)) (sunrise-tomorrow (first (theme-changer-sunrise-sunset-times (theme-changer-tomorrow))))) (let* ((--cl-rest-- (theme-changer-sunrise-sunset-times (theme-changer-today))) (sunrise-today (if (= (length --cl-rest--) 2) (car-safe (prog1 --cl-rest-- (setq --cl-rest-- ...))) (signal (quote wrong-number-of-arguments) (list nil (length --cl-rest--))))) (sunset-today (car --cl-rest--))) (let* ((theme (cond ((time-less-p now sunrise-today) (cons sunrise-today night-theme)) ((time-less-p now sunset-today) (cons sunset-today day-theme)) (t (cons sunrise-tomorrow night-theme)))) (next-change (if theme (car-safe (prog1 theme ...)) (signal (quote wrong-number-of-arguments) (list nil ...))))) (let ((old-theme (theme-changer-switch-theme old-theme theme))) (run-at-time (theme-changer-add-second next-change) nil (quote change-theme) day-theme night-theme old-theme)))))
  change-theme(solarized-light solarized-dark)
  eval((change-theme (quote solarized-light) (quote solarized-dark)) nil)

System Info 💻

• OS: darwin
• Emacs: 26.3
• Spacemacs: 0.300.0
• Spacemacs branch: develop (rev. f4f95d28f)
• Graphic display: t
• Distribution: spacemacs
• Editing style: hybrid
• Completion: ivy
• Layers:

(spacemacs-cfg config lang misc my-org)

• System configuration features: NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS THREADS

With the theme changing, the fonts change too. Any way to avoid that?

You've mentioned that you're looking for a maintainer. I find this package to be immensely useful, and would like to see it continued to be worked on and updated. I'm willing to take on the task if you're still looking for someone.

Hi, guys. This emacs plugin is very good. But I'm wondering that is there any kind of things like a hook can be run after the theme changed? The thing is I want to change the font weight after theme changed. If there is not, can anybody help me to modify the code? I've tried to add hook after load-theme, but it doesn't work. Thanks!

Can you help to fix this ?

_Debugger entered--Lisp error: (error "Too many arguments") (defvar theme-changer-post-change-hook nil ("c:/Users/abc/AppData/Roaming/.emacs.d/elpa/th..." . 1171) :type 'hook :group 'theme-changer) require(theme-changer) load-with-code-conversion("c:/Users/abc/AppData/Roaming/.emacs.d/init.el" "c:/Users/abc/AppData/Roaming/.emacs.d/init.el" t t) load("c:/Users/abc/AppData/Roaming/.emacs.d/init" noerror nomessage) startup--load-user-init-file(#f(compiled-function () #<bytecode 0xbd4630b4395cf5c>) #f(compiled-function () #<bytecode -0x1f3c686ddc0da035>) t) command-line() normal-top-level()_