Prevent transient from exiting AND from acting upon the *transient* buffer

[precompute]

I'm using Emacs 30 and Transient 0.4.1. I'm trying to make a Transient that can enable / disable modes.

(transient-define-prefix test-transient ()
  "Transient test."
  ;; :transient-suffix     'transient--do-stay
  ;; :transient-non-suffix 'transient--do-warn
  ["Heading 1"
   [("o" olivetti-mode
     ;; :transient t
     :description (lambda () (if olivetti-mode
                                 (propertize "ON" 'face '(bold success))
                               (propertize "OFF" 'face '(bold error)))))]])

The Transient defined in this example exits after o is pressed.

Uncommenting :transient t or transient--do-stay prevents the Transient from exiting after the command is executed, but the command is executed in the transient buffer instead of the buffer (or window) the Transient was called from.

How can I make the Transient stay after execution, and also act on the buffer (or window) it was called from? Uncommenting :transient t or transient--do-stay works on commit 51c50d (ancient, from December 2021) which I'm using on my old Emacs config.

(I use "(or window)" because I've previously been able to change the buffer in a window and still have the transient work on it)

[tarsius]

the command is executed in the transient buffer instead of the buffer (or window) the Transient was called from.

How did you make that determination? I don't think the code you provided would be able to demonstrate that issue. (It might be affected by such an issue, but it would be hard to tell what is going on.)

I don't have olivetti-mode, so I haven't tried with this.

Here is some other code that would be able to demonstrate that issue, but, for me at least, it instead demonstrates that things work as expected.

(defvar-local test-var t)

(transient-define-prefix test-transient ()
  [("s" test-set-test-var :transient t :description
    (lambda () (format "[stay] (from %s) %s" (current-buffer) test-var)))
   ("e" (lambda () (interactive) (test-set-test-var))
    :transient nil :description
    (lambda () (format "[exit] (from %s) %s" (current-buffer) test-var)))])

(defun test-set-test-var ()
  (interactive)
  (let ((v (random 100)))
    (message "(in %s) %s => %s" (current-buffer) test-var v)
    (setq test-var v)))

[precompute]

Sorry, I wrote a new message below instead of using the reply box here (just noticed the box).

[tarsius]

Not your fault. Github should work on making the UI more obvious. As it stands, more than 50% of what should have been "replies", are instead written as "new answers".

[precompute]

Calling message and enabling/disabling a mode are different, the mode acts on a buffer while the message is always in the echo area (buffer/window independent).

I've tried https://github.com/positron-solutions/transient-showcase as well, and every example there also only uses message.

You can try this instead:

(transient-define-prefix test-transient ()
  "Transient test."
  :transient-suffix     'transient--do-stay
  ;; :transient-non-suffix 'transient--do-warn
  ["Heading 1"
   [("o" olivetti-mode
     ;; :transient t
     :description (lambda () (if olivetti-mode
                                 (propertize "ON" 'face '(bold success))
                               (propertize "OFF" 'face '(bold error)))))
    ("l" display-line-numbers-mode
     ;; :transient t
     :description "Toggle Line Numbers")
    ("v" visual-line-mode
     :description "Visual Lines")
    ("m" mixed-pitch-mode
     :description "Mixed Pitch")]]
  ["Major Modes"
   [("0" "Clean Mode" clean-mode)]
   [("1" "Fundamental Mode" fundamental-mode)
    ("2" "Emacs Lisp Mode" emacs-lisp-mode)]])

[tarsius]

Calling message and enabling/disabling a mode are different, the mode acts on a buffer while the message is always in the echo area (buffer/window independent).

Yes of course, but that's not really relevant. message is just there so we can observe the effect. We could also just call (setq-local some-var 'some-unique-value) and then later manually inspect in what buffer the value of same-var is some-unique-value.

But let's use a mode. This is a minimal example, whose effect is easy to observe:

(transient-define-prefix test-transient ()
  [("r" ruler-mode :transient t :description
    (lambda ()
      (format "Ruler mode is %s in %s"
              (if ruler-mode "on" "off") (current-buffer))))])

This toggles the mode in the buffer that was current before (and actually also while) the transient buffer is being shown. If that isn't the case for you, then start with emacs -Q, and if not even that fixes it, provide detailed steps to reproduce.

But begin with uninstalling Transient, exiting Emacs, restarting Emacs, reinstalling Transient -- just in case.

[precompute]

Thank you for the example and the explanation! (current-buffer) was not *transient* for me.

I spent some time enabling and disabling things, and it turns out this wasn't an issue with Transient. It's instead an issue with shackle-mode (https://depp.brause.cc/shackle/), which I was using to enforce popup positions. I'm migrating from DOOM and wanted something easy, I guess I'll try to use display-buffer-alist instead.

[tarsius]

I've added a note about that package to https://github.com/magit/transient/wiki/FAQ. This package was the culprit before.