Learning GNU Emacs, 3rd Edition

Building Your Own Lisp Library

After you have become proficient at Emacs Lisp programming, you will want a library of Lisp functions and packages that you can call up from Emacs at will. Of course, you can define a few small functions in your .emacs file, but if you are writing bigger pieces of code for more specialized purposes, you will not want to clutter up your .emacs file—nor will you want Emacs to spend all that time evaluating the code each time you start it up. The answer is to build your own Lisp library, analogous to the Lisp directories that come with Emacs and contain all of its built-in Lisp code. After you have created a library, you can load whatever Lisp packages you need at a given time and not bother with the others.

Creating a library requires two simple steps. First, create a directory in which your Lisp code will reside. Most people create a elisp subdirectory of their home directory. Lisp files are expected to have names ending in .el (your .emacs file is an exception). The second step is to make your directory known to Emacs so that when you try to load a Lisp package, Emacs knows where to find it. Emacs keeps track of such directories in the global variable load-path, which is a list of strings that are directory names.

The initial value for load-path is populated with the names of the Lisp directories that come with Emacs, e.g., /usr/local/emacs/lisp. You will need to add the name of your own Lisp directory to load-path. One way to make this addition is ...