Doom Emacs single keystroke undo

Question

How can I have single keystroke undo using Doom Emacs with Emacs 27.2? I have already tried multiple suggestions on this site, so far none work. Perhaps Doom Emacs is the problem, or maybe it's that I'm using Emacs 27.2. Is there a new solution someone can share?

Answer 1

It is unknown why the O.P. is experiencing problems. The following method of installation and usage of a prior answer in a related thread appears to work correctly without any issues.

STEP #1: Install a fresh version of Doom. In my case, I renamed the existing ~/.emacs.d to preserve the contents and to enable git to create a new ~/.emacs.d in which to install Doom. In a terminal, run the command:

git clone --depth 1 https://github.com/hlissner/doom-emacs ~/.emacs.d

STEP #2: In the terminal, navigate with cd over to ~/.emacs.d/bin and run the command:

./doom install

Be patient while many packages are downloaded and installed.

STEP #3: I chose y when presented with the prompt/question:

Download and install all-the-icon's fonts? (y or n)

STEP #4: In the terminal, run the command:

./doom sync

STEP #5: Open up ~/.emacs.d/init.el, navigate to the bottom of the file, and insert the following snippet from the answer to the related question https://emacs.stackexchange.com/a/47349/2287

(when (timerp undo-auto-current-boundary-timer)
  (cancel-timer undo-auto-current-boundary-timer))

(fset 'undo-auto--undoable-change
  (lambda () (add-to-list 'undo-auto--undoably-changed-buffers (current-buffer))))

(fset 'undo-auto-amalgamate 'ignore)

Save the file.

STEP #6: Open or restart a recent version of Emacs, e.g., Emacs 27.2.

STEP #7: Open a new buffer. I am unfamiliar with vi and evil, and M-x seems to be disabled, so I used: M-: to access eval-expression. I typed (find-file "FOO"). I pressed the letter "i" to enable insert-mode to insert text into the current buffer. I typed the word: Hello. I used the keyboard shortcut to interactively call undo-fu-only-undo, which was bound by default on OSX El Capitan to s-z. Emacs undoes one keystroke at a time.

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INSTALL NOTES: In my case, OSX El Capitan comes with a pre-installed outdated version of Emacs at /usr/bin/emacs. It was necessary to modify the ~/.emacs.d/bin/doom script to use a current version of Emacs, or perhaps create an alias so that the script calls to $EMACS find a recent version. I also had to devise a method so that the files used to build Doom could find a more recent version of git. Finally, the file +azerty.el was uncooperative with the version of wgrep that I used when trying to modify the call to "git" -- I'm not sure why the file was uncooperative, but I went ahead and deleted the extra ^M carriage returns and modified the line with "git" to use an absolute path. However, I do not know whether that file is used when building Doom.