Short Story: el-get allows you to install and manage elisp code for Emacs. It supports lots of differents types of sources and is able to 'install' them, 'update' them and 'remove' them, but more importantly it will 'init' them for you.
That means it will care about require ing the 'features' you need, load ing the files, setting the 'Info' paths so that C-h i shows the new documentation you now depend on, and finally call your own :after function for you to setup the extension. Or call it a package.
How to Install it?
Here’s the 'lazy installer':
;; So the idea is that you copy/paste this code into your *scratch* buffer, ;; hit C-j, and you have a working el-get. (url-retrieve "https://github.com/dimitri/el-get/raw/master/el-get-install.el" (lambda (s) (end-of-buffer) (eval-print-last-sexp)))
You have to type C-j with the cursor at the end of the last line, but still on the line. 'C-j runs the command eval-print-last-sexp', so it will evaluate the code you’re looking at, and that will git clone el-get at the 'right place'.
Note that the first line conditional allows you to add this elisp code into your emacs init file directly.
What is this?
Of course, my emacs setup is managed in a private git repository. Some people on #emacs are using git submodules (or was it straight import) for managing external repositories in there, but all I can say is that I frown on this idea. I want an easy canonical list of packages I depend on to run emacs, and I want this documentation to be usable as-is. Enters el-get!
(setq el-get-sources '(cssh el-get switch-window vkill google-maps nxhtml xcscope yasnippet (:name magit :after (lambda () (global-set-key (kbd "C-x C-z") 'magit-status))) (:name asciidoc :type elpa :after (lambda () (autoload 'doc-mode "doc-mode" nil t) (add-to-list 'auto-mode-alist '("\\.adoc$" . doc-mode)) (add-hook 'doc-mode-hook '(lambda () (turn-on-auto-fill) (require 'asciidoc))))) (:name lisppaste :type elpa) (:name dictionary-el :type apt-get) (:name emacs-goodies-el :type apt-get))) (el-get)
So now you have a pretty good documentation of the packages you want installed, where to get them, and how to install them. For the advanced methods (such as elpa or apt-get), you basically just need the package name. When relying on a bare git repository, you need to give some more information, such as the URL to clone and the build steps if any. Then also what features to require and maybe where to find the texinfo documentation of the package, for automatic inclusion into your local Info menu.
The good news is that not only you now have a solid readable description of all that in a central place, but this very description is all (el-get) needs to do its magic. This command will check that each and every package is installed on your system (in el-get-dir) and if that’s not the case, it will actually install it. Then, it will init the packages: that means caring about the load-path, the Info-directory-list (and dir texinfo menu building) the loading of the emacs-lisp files, and finally it will require the features.
How to use it?
You see that el-get-sources exemple up there? It finishes with a single (el-get) call. That’s it. It will 'install' new sources on the list and only 'init' already installed ones.
The status of each package is tracked into ~/.emacs.d/el-get/.status.el (by default) and can get the values required, installed or removed.
Sync or async?
Most often you want el-get-install and el-get-build to stay out of the way and be 'asynchronous', so that you can continue using Emacs while your new package is getting ready. But imagine you’re starting up Emacs after a git pull on the other computer (after a commute, say), and there’s some newer packages for this instance to consider installing.
Now you want a synchronous install, right?
So, by default (el-get) is asynchronous, but you can ask for it to be sync, or to still be asynchronous but to wait until it finished before to give control back:
(el-get 'sync) (el-get 'wait)
You even get a progress report!
See the documentation of the el-get-sources variable for details.
Some sources are contributed to el-get directly, so that you only have to put in the el-get-sources the name of the package you want to install.
Should you need some local specific setup, you can do that by providing a partial sources missing the :type property: your local properties will get merged into the recipes one.
Also, the variable el-get-recipe-path allows you to maintain local recipes in case you either dislike the default one or are crafting some new one not commited to the main repository yet. But please do consider sending them over!
We do not intend to provide recipes for advanced types such as apt-get and elpa because there’s so little to win here, and maintaining a package list would take too much time.
Avoid make install that will move files into a proper destination place, that’s for distributors to care, like debian for example. In our case, you probably just want your package foo to be all installed into ~/.emacs.d/el-get/foo, right? So, no make install.
el-get will 'byte compile' the elisp for the package when its source definition includes a :compile property set to the list of files to byte compile (or to a single file), or all the .el files found in the package when there’s no :build command.
el-get offers a variety of specific hooks (read the source), and two general purposes hooks facilities: el-get-post-install-hooks and el-get-post-update-hooks, called with the package name as argument.
Some more commands?
- M-x el-get-sync
Synchronously make your current el-get status match el-get-sources, by installing and initializing all your packages.
- M-x el-get-cd
Will prompt for a package name, with completion, then open its directory with dired.
- M-x el-get-install
Will prompt for a package name, with completion, then install it following the source you’ve already setup. Depending on the type of the package, this will fail for an already installed package.
When using C-u, +el-get-install+ will allow for installing any package you have a recipe for, instead of only proposing packages from +el-get-sources+.
- M-x el-get-update
Will prompt for a package name, with completion, then update it. This will run the build commands and init the package again.
- M-x el-get-update-all
Will update all packages used in el-get-sources. Beware that using this function can lead to hours of settings review: more often than not updating a package requires some adjustments to your setup. Updating all of them at once will require reviewing almost all your setup.
- M-x el-get-remove
Will prompt for a package name, with completion, then remove it. Depending on the type of the package, this often means simply deleting the directory where the source package lies. Sometime we have to use external tools instead (apt-get, e.g.). No effort is made to unload the features.
When using C-u, +el-get-remove+ will allow for installing any package you have a recipe for, instead of only proposing packages from +el-get-sources+.
- M-x el-get-make-recipes
Will prompt for an existing directory where to output all your 'new' recipe files: one file for each entry in el-get-sources that is not just a symbol and that is not found anywhere in el-get-recipe-path.
The C-u alternatives are not provided for the el-get-update and el-get-init command, on the grounds that if you want to use them you probably should now have the package into your el-get-sources proper.
TODO: explain the symlinks in ~/.emacs.d/el-get. For now, read the source and try it out.
Please see the documentation for the el-get-methods and provide a patch!
Adding bzr support for example was only about writing 2 functions, mostly using copy paste. Here’s the patch: http://github.com/dimitri/el-get/commit/494551a9e75ebeb9ad043da175e6b2140d0d87d3
el-get will now save some package status information into the file el-get-status-file, it’s a property list of the package symbol and its status. The status is set to "required" when you enter el-get-install and is changed to installed upon successful completion of the installation, including the build.
Now, if you el-get-install an already installed package, this is an error. If the status is "required", a previous install failed, you have to el-get-remove the package before continuing. If the status is "installed", well, the package is known installed.
To reinit the status file you might need to execute the following code:
(mapc (lambda (p) (el-get-save-package-status p "installed")) (el-get-package-name-list))