Configuring Emacs using Org-mode: org-babel

Emacs Org-mode is a great tool, and includes support for the so called /literate programming/. In short, you write your documentation at first, and within the documentation you insert snippets of code that can be /run/ (executed, compiled) by Emacs itself in order to produce a /concrete result/.
And of course, Emacs can use itself Org-mode to auto-configure the experience!
The trick is to use a package called org-babel and start to write your configuration into an Org-mode file.

Quick, show me the code!

There are plenty of tutorials online about this subject, so I will not go into deep details here. However, there are two main actions to take in order to configure Emacs via Org-mode files:
  • configure a startup file to load org-babel and make it parse one file (or more) written in Org-Mode;
  • create an Org-mode file with emacs-lisp block of codes that will do the configuration.

Step 1: init.el

Edit the startup file init.el (under ~/.emacs.d/init.el) and place the following piece of code: 

(require 'org)
(org-babel-load-file
 (expand-file-name "emacs.org"
                   user-emacs-directory))


The above snippet of code will load a file named emacs.org, that must be in the same directory of the init.el one, and will parse it. In particular, user-emacs-directory tells to the expand-file-name function to use the ~/.eamcs.d folder, so that the Org-mode file will be ~/.emacs.d/emacs.org.

Step 2: write emacs.org

Now, write a usual Org-mode file named ~/.emacs.d/emacs.org and put your text, your comments and the block of codes that you need to configure Emacs. The code blocks must be of type emacs-lisp.
As a bare example: 

#+title: Emacs Configurtion File
#+author: Luca Ferrari


* Packages
** Configure packages

#+BEGIN_SRC emacs-lisp
      ;; Initialize package sources
      (require 'package)

      (setq package-archives '(("melpa" . "https://melpa.org/packages/")
                               ("melpa-stable" . "https://stable.melpa.org/packages/")
                               ("org" . "https://orgmode.org/elpa/")
                               ("elpa" . "https://elpa.gnu.org/packages/")))

      (package-initialize)



    (unless (package-installed-p 'use-package)
        (package-refresh-contents)
        (package-install 'use-package) )


  (setq use-package-verbose t)
  (setq use-package-always-ensure t)
    (require 'use-package)
 #+END_SRC

 
* User Interface Customization
** Menu, Tool and Scroll Bars
All the bars have a /mode/ toggle that can be set to ~-1~ to indicate it has to be deactivated.
The ~menu-bar-mode~ considers the top menu bar, while ~tool-bar-mode~ is for the graphical tool bar.
The ~scroll-bar-mode~ is for the lateral scroll bar, but unlike the ~tool-bar-mode~, disabling the scroll bar in a non graphical environment causes a startup.
For this reason, the scroll and tool bars are deactivated only if ~display-graphic-p~ is non ~nil~, to indicate the system is running with a graphical display.

The ~progn~ function allows the sequential evaluation of its body and returns the last evaluated expression.

#+BEGIN_SRC emacs-lisp
(menu-bar-mode -1)
(if (display-graphic-p)
    (progn
       (tool-bar-mode -1)
       (scroll-bar-mode -1) ) )
#+END_SRC


** Highlight Current Line
Activate highlight line mode globally, and set a background color.
Setting the foreground color to ~nil~ prevents the line to loose the syntax hightlight.
#+begin_src emacs-lisp
  (global-hl-line-mode 1)
  (set-face-background 'hl-line "#313131")
  (set-face-foreground 'highlight nil)
#+end_src

   
** Guru Mode
Let's use the Emacs keybindings to move!
#+begin_src emacs-lisp
  (use-package guru-mode
  :ensure t )
(setq guru-warn-only 1 )
#+end_src


As you can see the initial part of the file is the preamble (optional) of an Org-mode document.
The very first part is the installation and load of the `use-package, that is the system I use to automatically install packages.
**It is important you configure your package manager at the very beginning, so to use it later on in the rest of the document file, and I included it in the Org-mode so that I can easily drop such file on a fresh machine and get Emacs do all the stuff for me!

Conclusions

Emacs Org-mode based configuration is simple, thanks to org-babel, and can be a very interesting way to craft and share your own configuration in a less lispy mode and with a more human readable approach!

The article Configuring Emacs using Org-mode: org-babel has been posted by Luca Ferrari on November 26, 2021

Tags: emacs , org-mode