Emacs on August Feng

debugging Spacemacs initialization

Wed, 20 Aug 2025 00:00:00 +0000

About

Earlier today I introduced a bug somewhere in Emacs and decided to delete and reinstall Spacemacs, while keeping my ~/.spacemacs configuration.

This introduced another bug where auth-source was not able to read my Open API API anymore. This expression kept evaluating to nil:

  (auth-source-search
   :host "api.openai.com"
   :user "apikey"
   :require '(:secret)
   )

Progress

I noticed that if I evaluated auth-source-forget-all-cached, the expression above would successfully find my credentials.

Special Character Kill

Tue, 19 Aug 2025 00:00:00 +0000

About

I'm studying a few chapters from The Linux Programming Interface book, and I'm learning about how the terminal driver can interpret special characters.

The KILL character

The KILL character (typically sent by Control-U) should make the terminal driver to delete the current line on the terminal.

We can use stty -a to see what KILL is bound to:

speed 9600 baud; 102 rows; 271 columns;
lflags: icanon isig iexten echo echoe -echok echoke -echonl echoctl
	-echoprt -altwerase -noflsh -tostop -flusho pendin -nokerninfo
	-extproc
iflags: -istrip icrnl -inlcr -igncr ixon -ixoff ixany imaxbel iutf8
	-ignbrk brkint -inpck -ignpar -parmrk
oflags: opost onlcr -oxtabs -onocr -onlret
cflags: cread cs8 -parenb -parodd hupcl -clocal -cstopb -crtscts -dsrflow
	-dtrflow -mdmbuf
cchars: discard = ^O; dsusp = ^Y; eof = ^D; eol = <undef>;
	eol2 = <undef>; erase = ^?; intr = ^C; kill = ^U; lnext = ^V;
	min = 1; quit = ^\; reprint = ^R; start = ^Q; status = ^T;
	stop = ^S; susp = ^Z; time = 0; werase = ^W;

Normally, the shell will also implement a kill-line behaviour on Control-U though, so if the terminal driver doesn't clear it, at least the shell will:

Creating menu items with emacs

Mon, 21 Apr 2025 00:00:00 +0000

About

We need three things in order to create a new menu on MacOS for emacs.

Keymap

First we need to create a keymap. This is also used by modes to create keybindings.

  (defvar foobar (make-sparse-keymap "foobar"))

define-key

The define-key function is used to map keys to a function. For example, this following function will write "helloworld" on C-c z:

  (define-key (current-global-map) (kbd "C-c z") (lambda () (interactive) (message "helloworld")))

It's also used to create menu items:

lsp-mode and web-mode hanging on css completion

Wed, 16 Apr 2025 00:00:00 +0000

About

I'm using Spacemacs, and the Emacs UI hangs for a few seconds when I select a completion value while authoring css properties.

Studying the completion framework

The completion framework provided by Spacemacs is I'm using is company and the completion backend selected when I edit html is completion-capf which is bridge to the native completion system in Emacs.

We can see which completion backend is being used by using the M-x: company-diag command.

etags as xref backend functions

Fri, 14 Feb 2025 00:00:00 +0000

About

I built the TAGS file in some open source projects but Emacs's xref-find-definitions was failing me.

I remembered that I had encountered this issue a few weeks ago and completely forgot my learnings.

I'm going to be documenting them here now in hopes that I'll remember for next time.

Debugging

I authored a very bare c program and built the TAGS file. Emacs was successfully finding the definitions. So what's up?

How to number a list of lines in org mode

Sun, 02 Feb 2025 00:00:00 +0000

About

I never had to number a list of lines so many times until my most recent study on TCP sequence numbers.

How

Paste a bunch of lines, and use the string-rectangle command to insert "1." at the beginning:

hello

world

.

Finally, move the cursor to any of thes lines and press C-c:

hello

world

.

A study on default font in emacs on macos

Thu, 21 Nov 2024 00:00:00 +0000

About

An unconfigured Emacs on an unconfigured MacOS will use this font:

--Menlo-regular-normal-normal--12---*-m-0-iso10646-1

Why?

Discovery

The x-create-frame emacs lisp function will use the userFixedPitchFontOfSize case to identify the default monospace font.

This is defined in the nsfns.m file.

Minimal Reproducer (Sorta)

  int main(int argc, const char * argv[]) {
    @autoreleasepool {
      CTFontRef name = CTFontCreateUIFontForLanguage(kCTFontUIFontUserFixedPitch, 0, NULL);
      CGFloat size = CTFontGetSize(name);
      NSLog(@"User Fixed Pitch Font: %@, Default Size: %.2f", name, size);
    }
    return 0;
  }

2024-11-21 23:56:50.349 a.out[19798:994265] User Fixed Pitch Font: <CTFont: 0x135f06a70>{name = Menlo-Regular, size = 10.000000, matrix = 0x0, descriptor = <CTFontDescriptor: 0x600000808960>{attributes = { NSFontNameAttribute = "Menlo-Regular"; }>}}, Default Size: 10.00

Magit workflow for contributing to oss

Sat, 22 Jun 2024 00:00:00 +0000

About

It's been only a little while since I made a pull request to an open-source project and I forgot the conclusion I had about setting up my local git repository.

Conclusion

I structure my file system with git repositories from github so that it replicates the <OWNER>/<REPO> in github.

Earlier, I nearly duplicated the repository to augustfengd/<REPO> because the repository will technically exist as as fork and I will be pushing there. No.

Instant previews using grip

Wed, 19 Jun 2024 00:00:00 +0000

About

A few years ago, I had discovered a setup for live previewing markdown/org files in Emacs. It took me a little while to remember how I did that, and implement it again on my new work machine.

I don't want this to happen again, so I am documenting the steps for the future me.

Implementation

xwidgets support

Emacs needs to be buitl with xwidgets support.

Magit commit issues on wsl2

Sun, 18 Feb 2024 00:00:00 +0000

About

The magit package uses the with-editor package to spin up an emacsclient in order to run subprocesses. This is used when drafting commit messages.

With a vanilla installation of Ubuntu 22.04, I'm not able to spin up an emacsclient:

  emacsclient helloworld
  # emacsclient: can't connect to /run/user/1000//emacs/server: Permission denied
  # emacsclient: No socket or alternate editor.  Please use:
  # 
  #         --socket-name
  #         --server-file      (or environment variable EMACS_SERVER_FILE

I've fixed this by changing the ownership of that directory to myself: sudo chown ${USER}:${USER} $XDG_RUNTIME_DIR and it works!

What are spinoff and spinouts in magit

Thu, 14 Sep 2023 00:00:00 +0000

Spinoff

Let's assume the following working git tree:

* 465318a (HEAD -> foobar) helloworld
* f4dd687 (master) init

A magit-branch-spinoff will create a new branch foobaz which takes foobar's place, and foobar will be moved to the branch's upstream:

* 465318a (HEAD -> foobaz) helloworld
* f4dd687 (master, foobar) init

Spinout

A magit-branch-spinoff will perform the same operations of magit-branch-spinoff, however we'll stay on the current branch.

Opening Emacs from windows

Sun, 10 Sep 2023 00:00:00 +0000

About

For various reasons, I prefer running a Emacs from WSL. I also exclusively it with a window system.

Wouldn't it be nice to open Emacs directly from Windows?

Issue

In order to open Emacs, I run it from a shell as it requires some environment variables which are configured from the login scripts. As a result, I need to keep a terminal window open for that shell.

Learning gnus

Mon, 14 Aug 2023 00:00:00 +0000

Shortcuts

The group buffer

commands to change views

A A (gnus-group-list-active): list all groups that are available on the servers.

L , A u (gnus-group-list-all-groups): list all groups.

l (gnus-group-list-groups): list groups with unread articles.

t (gnus-topic-mode): toggle the minor topic mode.

Summary buffer

M-g (gnus-summary-rescan-group): show read messages. this seems to only work when all articles are read?

! or u (gnus-summary-tick-article-forward): tick the message.

Exploring org-agenda workflows

Mon, 26 Jun 2023 00:00:00 +0000

Cycling between agenda files

C-' : Cycle through the files in ‘org-agenda-files’.

Filtering agenda items

\ : Keep only those lines in the agenda buffer that have a specific tag.

ref: https://orgmode.org/manual/Filtering_002flimiting-agenda-items.html

Debugging Spacemacs packages

Thu, 22 Jun 2023 00:00:00 +0000

About

An on-going documentation where I save knowledge gained from debugging emacs related things.

spacemacs recipes

  (oref (configuration-layer/get-package 'lsp-mode) :location)

Referencing layer packages locally

using local

The Spacemacs' documentation includes an FAQ answer on How to override a layer package.

I have the emacs-lsp package cloned to /Users/august.feng/repositories/gh/emacs-lsp/lsp-mode, so I'll be creating a symbolic link to that, and respectively adding (lsp-mode :location local) to dotspacemacs-additional-packages.

Learning yasnippets package

Thu, 22 Jun 2023 00:00:00 +0000

Creating snippets

The command yas-new-snippet will open a form for creating snippets.

The # name: and # key: fields describe the name of the snippet, and the abbreviation of the snippets before expansion.

Authoring snippets

embedded lisp code in template

Wrap the lisp code with `. This will be evaluated upon expansion.

avoiding auto indentations

The leading space before $2 is deleted when the template is inserted. We need to use the directive # expand-env: ((yas-indent-line 'fixed)) to avoid that.

Debugging the jka-compr package

Tue, 20 Jun 2023 00:00:00 +0000

About

The jka-compr package allows us to read compressed files as if they were uncompressed. It uses an external tool in the backend, gunzip in the case of MacOS as seen in the source code.

Issue

There seems to be an issue with a locally compiled emacs (29.0) where Spacemacs ignores the jka-compr.elc files, and tries to load the compressed jka-compr.el.gz, which is a circular dependency / bootstrap issue.

Learning session with melpa and quelpa

Mon, 03 Apr 2023 00:00:00 +0000

About

These are some notes I kept when messing around with the melpa packaging system.

Setup

  ;; Cask file
  (source gnu)
  (source melpa)

  (depends-on "quelpa")

Code

  ;; this use melpa's recipe
  (quelpa
   'lsp-mode)

  ;; this will not use melpa's recipe
  (quelpa
   '(lsp-mode :fetcher github :repo "emacs-lsp/lsp-mode"))

  ;; ~:files~ is supported for file fetcher.
  (quelpa
   '(lsp-mode :fetcher file :files ("*.el" "clients/*.el") :path "~/repositories/gh/emacs-lsp/lsp-mode"))

Configure MacOS

Sun, 02 Apr 2023 00:00:00 +0000

disable "Search man Page Index in Terminal" shortcut

This keybinding is used by Rider's Find Action shortcut. I've disabled it manually following the first workaround suggested by JetBrains.