Here are conventions that you should follow when writing Emacs Lisp code intended for widespread use:
This convention is mandatory for any file that includes custom definitions. If fixing such a file to follow this convention requires an incompatible change, go ahead and make the incompatible change; don't postpone it.
Occasionally, for a command name intended for users to use, it is more convenient if some words come before the package's name prefix. And constructs that define functions, variables, etc., work better if they start with ‘defun’ or ‘defvar’, so put the name prefix later on in the name.
This recommendation applies even to names for traditional Lisp
primitives that are not primitives in Emacs Lisp—such as
copy-list. Believe it or not, there is more than one plausible
way to define
copy-list. Play it safe; append your name prefix
to produce a name like
If you write a function that you think ought to be added to Emacs under
a certain name, such as
twiddle-files, don't call it by that name
in your program. Call it
mylib-twiddle-files in your program,
and send mail to ‘firstname.lastname@example.org’ suggesting we add
it to Emacs. If and when we do, we can change the name easily enough.
If one prefix is insufficient, your package can use two or three alternative common prefixes, so long as they make sense.
provideat the end of each separate Lisp file. See Named Features.
requireto make sure they are loaded. See Named Features.
(eval-when-compile (require 'bar))
This tells Emacs to load bar just before byte-compiling
foo, so that the macro definition is available during
eval-when-compile avoids loading bar
when the compiled version of foo is used. It should be
called before the first use of the macro in the file. See Compiling Macros.
clpackage of Common Lisp extensions at run time. Use of this package is optional, and it is not part of the standard Emacs namespace. If your package loads
clat run time, that could cause name clashes for users who don't use that package.
However, there is no problem with using the
cl package at
compile time, with
(eval-when-compile (require 'cl)). That's
sufficient for using the macros in the
cl package, because the
compiler expands them before generating the byte-code.
-unload-hook, where feature is the name of the feature the package provides, and make it undo any such changes. Using
unload-featureto unload the file will run this function. See Unloading.
(defalias 'gnus-point-at-bol (if (fboundp 'point-at-bol) 'point-at-bol 'line-beginning-position))
eval-after-loadin libraries and packages (see Hooks for Loading). This feature is meant for personal customizations; using it in a Lisp program is unclean, because it modifies the behavior of another Lisp file in a way that's not visible in that file. This is an obstacle for debugging, much like advising a function in the other package.
utf-8-emacs(see Coding System Basics), and specify that coding in the ‘-*-’ line or the local variables list. See Local Variables in Files.
;; XXX.el -*- coding: utf-8-emacs; -*-
indent-sexp) using the default indentation parameters.
;; Copyright (C) year name ;; This program is free software: you can redistribute it and/or ;; modify it under the terms of the GNU General Public License as ;; published by the Free Software Foundation, either version 3 of ;; the License, or (at your option) any later version. ;; This program is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; You should have received a copy of the GNU General Public License ;; along with this program. If not, see <http://www.gnu.org/licenses/>.
If you have signed papers to assign the copyright to the Foundation, then use ‘Free Software Foundation, Inc.’ as name. Otherwise, use your name. See Library Headers.
 The benefits of a Common Lisp-style package system are considered not to outweigh the costs.