Names is designed as a practical, complete, robust, and debuggable tool which writes your namespaces for you.
It is part of Emacs and is available through GNU Elpa, so every Emacs user running at least 24.1 has access to it.
A Namespace implementation for Emacs-Lisp
The Names package aims to provide an implementation of namespaces in Emacs with four guiding principles:
- Actually useful and easy to grasp.
- Support any macro, function, or special-form available in emacs-lisp, even the ones defined by you or a third party.
- No-surprises, well-tested, and with clearly stated limitations.
- Support edebug and
eval-defun, and any other package developing tools.
Currently, Names is being supported on the entire Emacs 24 family (24.1–24.4). Any new changes or pull requests are tested on a Travis-CI machine. See the “tests” subdirectory for our test suite, and see .
The UsageExample file clearly displays and explains how to use Names in your package. There are few simple measures to take. Go have a look if you’re interested, I promise it’s worth it!
If you want deeper descriptions of use-cases, see TheNittyGritty.org.
Names offers a series of tools to make package writing more
convenient inside a namespace. These developer facilities are on this
separate file, so the file isn’t loaded on the user’s computer when
your package calls
To access them add the following line to your init file.
Edebug and eval-defun support
First and foremost, the
edebug-eval-defun command (bound to
C-M-x) is an essential tool for any package developer. Names
wouldn’t be a very useful utility if it prevented you from using this
Therefore, it provides the
names-eval-defun command, which is
edebug-eval-defun except it also works inside
namespaces. It will automatically be added to your
Expansion and comparison functions
names-print offer information when
something just doesn’t seem to make sense.
The name of this package is Names, always with a capital “N”.
Despite the word being plural, refer to it in the singular (e.g.,
“Names is an amazing achievement”). If possible consider giving it a
slight emphasis, such as: Names.
When there’s a risk of confusion or ambiguity, be it due to context or
lack of knowledge by the reader,
names.el is also acceptable.
Why a namespace package?
Plain and simple: Emacs doesn’t have namespaces, and it needs them.
Nic Ferrier has a great essay on the subject, and you might want to read an opposing opinion as well. Note that Names is very different from the solution he proposes, but it does solve the problem he had with other alternatives which left the debugger unusable.
Emacs takes the approach of prefixing every symbol name with the name
of the package. This successfully avoids name clashes between
packages, but it quickly leads to code that’s repetitive and annoying
to write. Below is an example from
package.el, the word ”package”
is repeated 7 times in a 10-line function.
Names doesn’t change this overall approach. It adheres to Emacs standards and is completely invisible to the end-user. Names simply gives you (the developer) a convenient way of writing code that adheres to this standard.
- At runtime, the right-hand-side will create the same definitions as the left-hand-side.
- At compilation, it will create the exact same compiled file (with no left-over reference to
Below are the packages on which I’ve tested Names. If you’re interested, try using it on one of your packages and let me know how it goes.
- Number of ert tests passed: Same as before namespacing (62).
- Reduction in code size: Approx. 2000 characters.
- Number of ert tests passed: All.
- Reduction in code size: Approx. 1000 characters (8%).
1000 characters is a lot when you consider s.el has the second
shortest namespace possible,
- Number of ert tests passed: Same as before namespacing (104).
- Number of ert tests passed: ALL.
No actual tests defined, but this package actually uses Names for real! And it’s alive and well.