info.haml

%h1 Info documentation

%h2#path Info file search path

The [Info manual](
http://www.gnu.org/software/texinfo/manual/info/html_node/Emacs-Info-Variables.html)
tells us about variable `Info-default-directory-list`:

.do
  .window<
    :preserve
      (<span class="keyword">eval-after-load</span> 'info
        '(<span class="keyword">progn</span>
           (push <span class="string">"/opt/local/share/info"</span> Info-default-directory-list)
           (push <span class="string">"~/.emacs.d/info"</span> Info-default-directory-list)))

The first is the directory for info files installed by my package manager
(macports); modify the path according to your own system. The second directory
is where we'll install info files manually.


%h2#glibc glibc

[`glibc`]( http://www.gnu.org/software/libc/) ("gee lib cee") is the GNU
implementation of `libc`, the Unix standard C library. Don't confuse it with
`glib`, which is a library from the GNOME desktop project.

If you're not developing for a GNU/Linux system, but you don't find
`info`-format documentation for your system's own `libc`, you might still find
the GNU docs useful. `glibc` follows the ISO C 99 and POSIX standards, and its
documentation is always careful to point out where a feature is non-standard.
Common Unix variations are covered (e.g. the BSD and SysV styles of signal
handling).

.do
  Download "Info document (gzipped tar file)" from [the GNU website](
  http://www.gnu.org/software/libc/manual/).

  Untar into `~/.emacs.d/info/`

  `cd ~/.emacs.d/info`  
  `install-info libc.info dir`

`install-info` is provided by the texinfo package, which you can install with
your system's package manager.

The generated `dir` file contains an entry for every function and constant in
libc. These entries are added to your top-level Info menu. It is easy to remove
these from the top-level menu (you will still be able to find them via Info's
`i`ndex command or by searching): The `dir` file is plain text, so you can edit
it and remove those entries. Leave the single libc entry under "Libraries".

Now visit a C file and use `info-lookup-symbol` to look up, say, `socket`. Go
`u`p to the main sockets node for introductory material.


%h2#python Python

Install [pydoc-info.el](
https://bitbucket.org/jonwaltman/pydoc-info/src/default/pydoc-info.el) (we
covered elisp package installation in a [previous chapter](
customize_colors.html#packages)) and follow the instructions under "Setup and
Install" in [pydoc-info's README](
https://bitbucket.org/jonwaltman/pydoc-info).


%h2#perl Perl

I've found [info docs for perl 5.6](
http://www.cpan.org/doc/manual/texinfo/perl5/) (over a decade old now). If you
know of a more recent version, or know how to build info files from the latest
perl docs, please send me detailed instructions.

And spread the word! It's a shame that such a well-integrated documentation
system hasn't received more support from popular software distributions.