customize_colors.haml

%h1 Fix that awful color scheme

The default Emacs color scheme is affectionately known as "angry fruit salad".

%h2#default Default font

["Fonts" in the Emacs manual](
http://www.gnu.org/software/emacs/manual/html_node/emacs/Fonts.html)[[1]] says:

.do
  Click on 'Set Default Font' in the 'Options' menu. To save this for future
  sessions, click on 'Save Options' in the 'Options' menu.[[2]]

"DejaVu Sans Mono" is a good choice (also known as "Bitstream Vera Sans Mono",
or "Menlo" on OS X 10.6+). Do choose a fixed-width font, even if you like
proportional fonts for programming. We'll cover Emacs's handling of
proportional fonts later.

The "Save Options" menu command automatically modified your init file with the
new settings (and told you so in the echo area, now in the `*Messages*` buffer
if you missed it).

There is a [known bug]( http://debbugs.gnu.org/cgi/bugreport.cgi?bug=2845) on
OS X that prevents "Save Options" from saving changes to the default font. OS X
users will have to use the `customize-face` mechanism I explain below,
specifying `default` as the face name.


%h2#colors Syntax highlighting colors

[Font Lock mode](
http://www.gnu.org/software/emacs/manual/html_node/emacs/Font-Lock.html) is the
minor mode responsible for syntax highlighting. You can read up on font-lock
mode if you want to figure out how Emacs decides what is a comment or a keyword
or a variable, or how to add your own keywords.

But to merely change the colors:

.do
  Figure out the name of the face you want to change: `describe-face` (defaults
  to the face at point) or `list-faces-display`.

.do
  `modify-face` will prompt you for a face and for each attribute to change.
  Leave attributes as "unspecified" (the default) to inherit from the default
  face. When it comes to the foreground and background colors, you can use the
  predefined colors shown by tab-completion, or you can specify RGB hex values
  like `#3f7f5f`.

.do
  `customize-face` brings up the "easy customization" interface I warned you
  against in the previous chapter. Click the `State` button and select `Save
  for Future Sessions`. (You can make changes here too, but I prefer
  `modify-face` because it gives you tab-completion on the possible values for
  each attribute.)

Apart from `describe-face`, which I found in the Help menu, I found all these
in the Emacs manual under ["Faces"](
http://www.gnu.org/software/emacs/manual/html_node/emacs/Faces.html),
["Standard Faces"](
http://www.gnu.org/software/emacs/manual/html_node/emacs/Standard-Faces.html)
and ["Customizing Faces"](
http://www.gnu.org/software/emacs/manual/html_node/emacs/Face-Customization.html).

Now let's figure out how to bypass the "easy customization" interface:

.do
  Visit your init file to see what "easy customization" added. If you already
  had the file open, you may need `revert-buffer` to see the latest changes.

.titlebar<
  init.el
.window.default.new-comment-face<
  :preserve
    (custom-set-variables
      <span class="comment">;; custom-set-variables was added by Custom.
      ;; If you edit it by hand, you could mess it up, so be careful.
      ;; Your init file should contain only one such instance.
      ;; If there is more than one, they won't work right.</span>
     )
    (custom-set-faces
      <span class="comment">;; custom-set-faces was added by Custom.
      ;; If you edit it by hand, you could mess it up, so be careful.
      ;; Your init file should contain only one such instance.
      ;; If there is more than one, they won't work right.</span>
     '(default ((t (<span class="builtin">:height</span> 120 <span class="builtin">:family</span> <span class="string">"Menlo"</span>))))
     '(font-lock-comment-face ((t (<span class="builtin">:foreground</span> <span class="string">"#3f7f5f"</span>)))))
    

You could configure the remaining font-lock faces by adding arguments to the
`custom-set-faces` form, but they might be overwritten if you use the easy
customization framework in future. Inspired by the name `custom-set-faces`, I
searched for functions beginning with `set-face` and found
`set-face-attribute`:

.window<
  :preserve
    (set-face-attribute 'default nil <span class="builtin">:family</span> <span class="string">"Menlo"</span> <span class="builtin">:height</span> 120)
    (set-face-attribute 'font-lock-comment-face nil <span class="builtin">:foreground</span> <span class="string">"#3f7f5f"</span>)
    (set-face-attribute 'font-lock-string-face nil <span class="builtin">:foreground</span> <span class="string">"#4f004f"</span>)
    (set-face-attribute 'font-lock-constant-face nil <span class="builtin">:foreground</span> <span class="string">"#4f004f"</span>)
    (set-face-attribute 'font-lock-keyword-face nil <span class="builtin">:foreground</span> <span class="string">"#00003f"</span>)
    (set-face-attribute 'font-lock-builtin-face nil <span class="builtin">:foreground</span> <span class="string">"#00003f"</span>)
    (set-face-attribute 'font-lock-type-face nil <span class="builtin">:foreground</span> <span class="string">"#000000"</span>)
    (set-face-attribute 'font-lock-function-name-face nil
                        <span class="builtin">:foreground</span> <span class="string">"#000000"</span> <span class="builtin">:weight</span> 'bold)
    (set-face-attribute 'font-lock-variable-name-face nil
                        <span class="builtin">:foreground</span> <span class="string">"#000000"</span> <span class="builtin">:weight</span> 'bold)

The above settings produce a very conservative dark-on-white color scheme. I
like it because in many languages it highlights variable and function
*definitions* but not their uses.

For all the face attribute names see ["Face Attributes"](
http://www.gnu.org/software/emacs/manual/html_node/elisp/Face-Attributes.html)
in the Emacs Lisp manual. As to elisp syntax, [keyword symbols](
http://www.gnu.org/software/emacs/manual/html_node/elisp/Symbol-Type.html) like
`:foreground` and `:weight` are constants (that evaluate to themselves so you
don't have to quote them).


%h2#diff diff-mode

While we're on colors, let's add some helpful coloring to `diff-mode` (which
we came across earlier, in the section on the `vc` version control
interface).[[4]]

.do
  .titlebar<
    init.el
  .window<
    :preserve
      (<span class="keyword">eval-after-load</span> 'diff-mode
        '(<span class="keyword">progn</span>
           (set-face-foreground 'diff-added <span class="string">"green4"</span>)
           (set-face-foreground 'diff-removed <span class="string">"red3"</span>)))

`eval-after-load` does what it says: The first time `diff-mode` is loaded,
evaluate the following form. Emacs tends not to load every elisp package on
startup, but waits until you actually *use* `diff-mode` to load it.

If you used `(set-face-foreground 'diff-added ...)` directly in your init file,
you would get the error "invalid face diff-added". You could explicitly load
`diff-mode` (using `require`) in your init file, but that would increase
Emacs's startup time—ever so slightly—every time you run Emacs in the
terminal for a quick job that won't even use `diff-mode`.

`eval-after-load` takes a single form to evaluate, but we want to make two
function calls, so we wrap them in `progn` which merely evaluates a bunch of
forms sequentially. We quote it so that it doesn't get evaluated right now,
before even being passed to `eval-after-load`.

.figure
  .titlebar<
    diff-mode.el.gz
  .window<
    :preserve
      &nbsp;
      <span class="comment-delimiter">;; </span><span class="comment">provide the package
      </span><span class="esk-paren">(</span><span class="keyword">provide</span> '<span class="constant">diff-mode</span><span class="esk-paren">)</span>

The first argument to `eval-after-load` has to match the name that the package
`provide`s (this usually matches the name of the command to enable the mode,
but to double-check: `C-h f diff-mode`, follow the link to `diff-mode.el.gz`,
and find the `provide` form near the bottom).


%h2#themes Color themes

*Note: This section and the next, which deal with the `color-theme` package,
were written for Emacs 23. `color-theme` is obsolete in Emacs 24, so I need
to find a better example for installing third-party packages.*

Maybe you already have a favourite color theme, like [Zenburn](
http://slinky.imukuppi.org/zenburnpage/) or [Solarized](
http://ethanschoonover.com/solarized). There are Emacs implementations
([Zenburn]( https://github.com/bbatsov/zenburn-emacs), [Solarized](
https://github.com/sellout/emacs-color-theme-solarized)) built on top of the
[`color-theme`]( http://www.nongnu.org/color-theme/) minor mode. `color-theme`
is a third-party package; it doesn't come with Emacs.

Note that Emacs 24 provides a built-in mechanism for defining multiple color
themes. Nevertheless, I'll walk you through the process of installing
third-party packages using `color-theme` and the Solarized theme as examples.

Emacs 24 also comes with a package management system, so--as long as the
package's author has taken advantage of the new mechanism--the manual
installation procedure described below will not be necessary either.


%h2#packages Installing third-party elisp packages

I'll assume that you are keeping your `~/.emacs.d` under version control using
git.[[3]]

`color-theme`'s [installation instructions](
http://www.nongnu.org/color-theme/#sec5) recommend using your package manager
(`apt-get install emacs-goodies-el` or `port install color-theme-mode.el`,
etc.) but I prefer to manage all my Emacs extensions in a single place. That
place is my `~/.emacs.d` directory, because I will eventually want an extension
that isn't provided by my system's package manager.

.do
  Download the [color-theme.6.6.0.tar.gz](
  http://download.savannah.nongnu.org/releases/color-theme/) and extract into
  `~/.emacs.d`.

  `git add color-theme.6.6.0;`  
  `git commit -m "color-theme 6.6.0 from http://www.nongnu.org/color-theme/";`

.do
  Add the color-theme directory to your Emacs `load-path`:
  -#
  .titlebar<
    init.el
  .window<
    :preserve
      (add-to-list 'load-path <span class="string">"~/.emacs.d/color-theme-6.6.0"</span>)

.do
  And actually load it:
  -#
  .window<
    :preserve
      (<span class="keyword">require</span> '<span class="constant">color-theme</span>)

Now you can select a theme with `color-theme-select`.


%h2#github Installing packages from github

The Solarized color theme for Emacs is [available on github](
https://github.com/sellout/emacs-color-theme-solarized). If you are keeping
your `~/.emacs.d` under version control using git, you can use git submodules
to simplify the management of such third-party packages.

.do
  `cd ~/.emacs.d;`  
  `git submodule add https://github.com/sellout/emacs-color-theme-solarized.git;`

In future you can use `git pull` from `~/.emacs.d/emacs-color-theme-solarized/`
to get the latest changes.

.do
  Add `~/.emacs.d/emacs-color-theme-solarized/` to your Emacs `load-path`, and
  require `'color-theme-solarized`, as you did for the `color-theme` package.

Now you can activate the theme with `color-theme-solarized-light` (or `-dark`).


%h2#size Increasing the font size

`C-x C-+`, `C-x C--`, and `C-x C-0`. See ["Temporary Face Changes"](
http://www.gnu.org/software/emacs/manual/html_node/emacs/Temporary-Face-Changes.html).


%h2#variable-pitch variable-pitch-mode

You can toggle between fixed- and variable-width fonts in a particular buffer
with `variable-pitch-mode`. The face to customize is `variable-pitch`.

To automatically enable `variable-pitch-mode`, add it to the hooks for all the
major modes where you want it to take effect. For example, to `text-mode-hook`
for editing plain text.

If you really want it *everywhere*, I suppose there's no harm in setting the
`default` face to a proportional font. The great advantage of
`variable-pitch-mode`, though, is that it is so easy to switch between
proportional- and fixed-width fonts when you come across some ascii art or an
ascii table in a comment.


#footnotes
  [[1]]:
  I found this—after some dead ends—with Info's `i`ndex command, typing
  "font", tab-completing, and trying whatever looked promising. I could just
  have explored the Options menu instead, but—silly me—I had disabled the
  menus because people on the internet said "real Emacs power users disable the
  menus." That might make sense on a text terminal, where you can't click the
  menu anyway, but on OS X, where there's only one menu bar at the top of the
  screen, it's just silly. See the next footnote.

  [[2]]:
  If you have disabled the menu, perhaps because you're using an init file
  copied from someone else or something like the [Emacs starter kit](
  http://github.com/technomancy/emacs-starter-kit), you can re-enable it just
  for this session with `M-x menu-bar-mode`.

  [[3]]:
  `cd ~/.emacs.d; git init .; git add init.el; git status; git diff --cached;`  
  `git commit -m "My emacs init file."`

  [[4]]:
  This customization—with several others—is borrowed from the [Emacs
  Starter Kit]( https://github.com/technomancy/emacs-starter-kit).