Package.el
package.el is the built-in package manager in Emacs 24.
| Description | Package Manager |
|---|---|
| Author | Tom Tromey |
| Maintainer | FSF |
| Source | http://repo.or.cz/w/emacs.git/blob_plain/HEAD:/lisp/emacs-lisp/package.el |
| Part of Emacs | Since Emacs 24 |
Install package.el on Emacs 23
package.el is bundled with Emacs 24, but it’s not bound to Emacs 23. Before it became part of Emacs it was an external package, known as package.el that was tied to repository called ELPA (Emacs Lisp Package Archive). So even if you’re an Emacs 23 user you can copy the latest version of package.el from here and enjoy it.
Alternatively, you can use the great el-get, another package manager for emacs (23 and others) which uses a diversity of sources, included ELPA.
Configuration
Put the following snippet of code near the beginning of your Emacs config, since you’ll definitely want packages installed via package.el to be initalized before you start tweaking them.
(require 'package)
(package-initialize)
Select Packages from the List
package.el connects to a list of package repositories, retrieves the list of the packages there, presents it to you in a interactive fashion and lets you install the packages you like (of course you can also remove the ones you don’t like). package.el understands the dependencies between packages and if one package requires others to run they will be installed automatically (which is really neat).
The magic starts with the command M-x package-list-packages. At this point you should see something in the lines of this.
You can navigate the list of packages, mark the ones you want to install with the “i” key or the ones you want removed with the “d” key and when you’re done you can press the “x” key to execute the scheduled actions.
A little drawback is that some packages won't load automatically at startup. Be sure to read the package description (press Enter), you may have to add a few lines to your .emacs.
Initially package.el didn’t provide the option to update a package, but that is fixed by now. You can press “U” (package-menu-mark-upgrades) to mark all the packages that need an update. To execute all the updates press “x”.
How to add additional repository
The list of available packages is short because the official Emacs 24 package repository has strict licensing (and source code) requirements to include a package there. Luckily there are a number of community-maintained package.el repos around with much more relaxed requirements. The oldest such repository is Marmalade, created by Natalie Weizenbaum of Sass and Haml fame. You can include it in your package-archives list like this:
(add-to-list 'package-archives '("marmalade" . "http://marmalade-repo.org/packages/"))
Marmalade provides a web based UI for package upload and search (both quite buggy unfortunately) and the ability to share the maintenance of a package between several people, who’ll be able to upload new version of the package. There’s also a Emacs Lisp Marmalade tool, that allows you to submit packages directly from Emacs.
There's also MELPA, which is the largest and most comprehensive package repository: it builds packages directly from the source-code control systems of upstream developers, which can then conveniently be installed by end users via package.el.
Install packages automatically on startup
Using the package.el UI is ok if you’re a casual Emacs user, but what if you have a custom Emacs configuration, stored under version control, that you’d like to instantly deploy on any OS/machine (like Emacs Prelude). Here in play comes package.el’s programmer interface. In Emacs Prelude I use the following code to install a list of required packages automatically on Emacs startup (if necessary):
;; Comment out if you've already loaded this package...
(require 'cl-lib)
(defvar my-packages
'(ack-and-a-half auctex clojure-mode coffee-mode deft expand-region
gist groovy-mode haml-mode haskell-mode inf-ruby
magit magithub markdown-mode paredit projectile python
sass-mode rainbow-mode scss-mode solarized-theme
volatile-highlights yaml-mode yari zenburn-theme)
"A list of packages to ensure are installed at launch.")
(defun my-packages-installed-p ()
(cl-loop for p in my-packages
when (not (package-installed-p p)) do (return nil)
finally (return t)))
(unless (my-packages-installed-p)
;; check for new packages (package versions)
(package-refresh-contents)
;; install the missing packages
(dolist (p my-packages)
(when (not (package-installed-p p))
(package-install p))))
This code check if all of the packages in the list are installed and if any of them are not installed if refreshes the local package database (in the case a required package for recently added to the remote repo) and installs them.
use-package
But the use-package macro (by J. Wingley, Emacs maintainer) also helps in doing that, and more. It allows to declare packages, install and load them asynchronously and declare their configuration.
Cask
Cask is a project management tool for Emacs that helps automate the package development cycle; development, dependencies, testing, building, packaging and more.
Cask can also be used to manage dependencies for your local Emacs configuration.
How to publish it to Marmalade
To be able to publish a package to Marmalade (or another repo) it should comform a standardized structure. A single-file package might look like this:
;;; sass-mode.el --- Sass major mode
;; Copyright 2007-2010 Natalie Weizenbaum
;; Author: Natalie Weizenbaum <nex342@gmail.com>
;; URL: http://github.com/nex3/sass-mode
;; Version: 3.0.20
;; Package-Requires: ((haml-mode "3.0.20"))
;; Code goes here
;;; sass-mode.el ends here
A multi-file package should have an additional file named `<name>-pkg.el` that should look like this:
(define-package "sass-mode" "3.0.20"
"Sass major mode"
'((haml-mode "3.0.20")))
package.el Repositories
Try a package without installing it
That is the goal of Try (on MELPA). Once installed, you can M-x try RET a-package [or url] RET. Packages from ELPA will be stored in a temporary directory by default.
See also
El-get, another excellent package manager
Automated package updates
with auto-package-update, on MELPA.
Try packages without installing them
This is possible with the package Try (on melpa). Packages will be stored in a temporary directory by default.
To try out a package you can run:
M-x try RET multiple-cursors RET
you can also put an url pointing to a .el file.