This afternoon I have changed the way my emacs and emacspeak initialization works.

Until now I have always used the file:

~/.emacs

For my initialization. But today, in reading about how emacs initialization and library-loading works, to try to understand how T.V. Raman does it and how his files in the git repository all hang together, I have made a discovery which has made me understand things a lot better and change my strategy.

Initialization Files

emacs will look for any of these files for it's initialization:

• ~/.emacs
• ~/.emacs.el
• ~/.emacs.d/init.el

So, I changed from using ~/.emacs to ~/.emacs.d/init.el.

Not only that but I have made some other discoveries, things which I did not know about before.

In our .emacs files we have usually had two blocks of lisp that begin with:

• (custom-set-variables ...
• (custom-set-faces ...

These two blocks of code are places into which changes are made when the emacs customization screens are used to make adjustments, hence the commentary in these blocks which warn about editing them by hand and not having more than one occurrence of each block.

Now, of course when adding stuff to the emacs initialization files by hand it is very easy to screw something up and stop the initialization from working.

When running emacspeak this is always immediately obvious because it comes up talking very, very slowly. Assuming of course you have emacspeak configured to talk more quickly than the default.

It is possible, it seems, to place the custom-set-variables and custom-set-faces code blocks into a separate file, name it as the custom file and then load it from the main initialization file.

So, bearing in mind we are now using ~/.emacs.d/init.el as our initialization file, place these two lines at the top of it:

(setq custom-file "~/.emacs.d/custom.el")
(load custom-file)

The first of these lines instructs emacs that we want to use a different file from our main initialization file for custom changes made by the emacs customization mechanism.

The second line instructs emacs to load it.

Now we can merrily add other stuff to ~/.emacs.d/init.el, knowing that we are at no risk of messing up those customizations added with the emacs mechanism.

Loading Personal Libraries

Instead of loading everything we want in our initialization file, we can split it up, and make it much more modular. In this way we can tinker with something new, and when something breaks, we know more easily what broke it and probably how to fix it.

The first thing we need to do, again in our shiny new ~/.emacs.d/init.el file, is to add some paths to the load-path variable in emacs. It is this variable which acts a bit like the $PATH environment variable in the bash shell.

Put this fragment of code in your ~/.emacs.d/init.el file, just underneath the top two lines which specify and load the custom file:

;; add some paths to load-path
(let ((default-directory "~/.emacs.d/lisp/"))(setq load-path
(append
(let ((load-path (copy-sequence load-path))) ;; Shadow
(append
(copy-sequence (normal-top-level-add-to-load-path '(".")))
(normal-top-level-add-subdirs-to-load-path)))
load-path)))

This will add:

~/.emacs.d/lisp

And all of the sub-directories thereof to the load-path variable. Well, not ALL the sub-directories. It will ignore things like version-control related paths, sub-directory names that start with a dot etc., very useful if you want to put your initialization stuff in git or CVS.

Now we can add a whole bunch of load-library directives below this to load individual personal libraries of lisp code:

(load-library "elpa-prepare.el")
(load-library "markdown-prepare")
(load-library "rst-prepare.el")
(load-library "abbrev-prepare")
(load-library "c-code-folding-prepare.el")

These are just a few libraries I have created from splitting off the code which I previously used to have in my ~/.emacs file.

It should be obvious from the names what each library is for.

What was left in ~/.emacs?

There were a few lines of code remaining in my original ~/.emacs file which I left in the new initialization file:

(setq-default truncate-lines t)
(setq inhibit-splash-screen t)

Before I did this work today it was very hard to wade through all of the custom stuff, the markdown initialization code, the rst initialization code, and find these lines.

Conclusion

By doing this stuff this afternoon I think I have:

• Split my original emacs initialization file into multiple library files which I load individually
• Split my manually added initialization code from the code added and changed by the Emacs customization mechanism, which should make identifying errors easier
• Dramatically increased the modularity of my initializations, making it more scalable
• Made tinkering with emacs configuration less scary and hence more inclined to get done
• Learned some valuable stuff about Emacs and Emacs Lisp

Note About load-library and .elc Files

By adding the path to our personal-libraries to the load-path variable we can leave out the .el extension of our libraries.

If byte-compiled versions of any of our libraries exist in .elc files, these will be loaded in preference to .el files, giving us an appreciable speed advantage.

To batch compile all the .el files in ~/.emacs.d/lisp:

emacs -batch -f batch-byte-compile *.el

The above will create .elc versions of each of the .el files. These will be the files which are loaded in preference to the .el files.