Copyright (C) 2006-2013 Free Software Foundation, Inc.
See end for license conditions.


			Contributing to Emacs

Emacs is a collaborative project and we encourage contributions from
anyone and everyone.  If you want to contribute in the way that will
help us most, we recommend (1) fixing reported bugs and (2)
implementing the feature ideas in etc/TODO.  However, if you think of
new features to add, please suggest them too -- we might like your
idea.  Porting to new platforms is also useful, when there is a new
platform, but that is not common nowadays.

For documentation on how to develop Emacs changes, refer to the Emacs
Manual and the Emacs Lisp Reference Manual (both included in the Emacs
distribution).  The web pages in http://www.gnu.org/software/emacs
contain additional information.

You may also want to submit your change so that can be considered for
inclusion in a future version of Emacs (see below).

If you don't feel up to hacking Emacs, there are many other ways to
help.  You can answer questions on the mailing lists, write
documentation, find and report bugs, check if existing bug reports
are fixed in newer versions of Emacs, contribute to the Emacs web
pages, or develop a package that works with Emacs.

Here are some style and legal conventions for contributors to Emacs:


* Coding Standards

Contributed code should follow the GNU Coding Standards.

If it doesn't, we'll need to find someone to fix the code before we
can use it.

Emacs has certain additional style and coding conventions.

Ref: http://www.gnu.org/prep/standards/
Ref: GNU Coding Standards Info Manual
Ref: The "Tips" Appendix in the Emacs Lisp Reference.


* Copyright Assignment

The FSF (Free Software Foundation) is the copyright holder for GNU Emacs.
The FSF is a nonprofit with a worldwide mission to promote computer
user freedom and to defend the rights of all free software users.
For general information, see the website http://www.fsf.org/ .

Generally speaking, for non-trivial contributions to GNU Emacs we
require that the copyright be assigned to the FSF.  For the reasons
behind this, see: http://www.gnu.org/licenses/why-assign.html .

Copyright assignment is a simple process.  If you live in the US, you
can do it entirely electronically.  We can help you get started, and
answer any questions you may have (or point you to the people with the
answers), at the emacs-devel@gnu.org mailing list.

A copyright disclaimer is also a possibility, but we prefer an assignment.
We can accept small changes (roughly, fewer than 15 lines) without
an assignment.  This is a cumulative limit (e.g. three separate 5 line
patches) over all your contributions.

* Getting the Source Code

The latest version of Emacs can be downloaded using Bazaar from the
Savannah web site.  It is important to write your patch based on the
latest version.  If you start from an older version, your patch may be
outdated (so that maintainers will have a hard time applying it), or
changes in Emacs may have made your patch unnecessary.

After you have downloaded the Bazaar source, you should read the file
INSTALL.BZR for build instructions (they differ to some extent from a
normal build).

Ref: http://savannah.gnu.org/projects/emacs


* Submitting Patches

Every patch must have several pieces of information before we
can properly evaluate it.

When you have all these pieces, bundle them up in a mail message and
send it to the developers.  Sending it to bug-gnu-emacs@gnu.org
(which is the bug/feature list) is recommended, because that list
is coupled to a tracking system that makes it easier to locate patches.
If your patch is not complete and you think it needs more discussion,
you might want to send it to emacs-devel@gnu.org instead.  If you
revise your patch, send it as a followup to the initial topic.

** Description

For bug fixes, a description of the bug and how your patch fixes this
bug.

For new features, a description of the feature and your implementation.

** ChangeLog

A ChangeLog entry as plaintext (separate from the patch).

See the various ChangeLog files for format and content.  Note that,
unlike some other projects, we do require ChangeLogs also for
documentation, i.e. Texinfo files.

Ref: "Change Log Concepts" node of the GNU Coding Standards Info
Manual, for how to write good log entries.

** The patch itself.

Please use "Context Diff" format.

If you are accessing the Bazaar repository, make sure your copy is
up-to-date (e.g. with `bzr pull'), then use
        bzr diff --no-aliases --diff-options=-cp
Else, use
	diff -cp OLD NEW

If your version of diff does not support these options, then get the
latest version of GNU Diff.

** Mail format.

We prefer to get the patches as inline plain text.

Please be aware of line wrapping which will make the patch unreadable
and useless for us.  To avoid that, you can use MIME attachments or,
as a last resort, uuencoded gzipped text.

** Please reread your patch before submitting it.

** Do not mix changes.

If you send several unrelated changes together, we will ask you to
separate them so we can consider each of the changes by itself.

** Do not make formatting changes.

Making cosmetic formatting changes (indentation, etc) makes it harder
to see what you have really changed.


* Coding style and conventions.

** Mandatory reading:

The "Tips and Conventions" Appendix of the Emacs Lisp Reference.

** Avoid using `defadvice' or `eval-after-load' for Lisp code to be
included in Emacs.

** Remove all trailing whitespace in all source and text files.

** Use ?\s instead of ?  in Lisp code for a space character.


* Supplemental information for Emacs Developers.

** Write access to the Emacs repository.

Once you become a frequent contributor to Emacs, we can consider
giving you write access to the Bazaar repository.


** Emacs Mailing lists.

Discussion about Emacs development takes place on emacs-devel@gnu.org.

Bug reports and fixes, feature requests and implementations should be
sent to bug-gnu-emacs@gnu.org, the bug/feature list.  This is coupled
to the tracker at http://debbugs.gnu.org .

You can subscribe to the mailing lists, or see the list archives,
by following links from http://savannah.gnu.org/mail/?group=emacs .

** Document your changes.

Think carefully about whether your change requires updating the
documentation.  If it does, you can either do this yourself or add an
item to the NEWS file.

If you document your change in NEWS, please mark the NEWS entry with
the documentation status of the change: if you submit the changes for
the manuals, mark it with "+++"; if it doesn't need to be documented,
mark it with "---"; if it needs to be documented, but you didn't
submit documentation changes, leave the NEWS entry unmarked.  (These
marks are checked by the Emacs maintainers to make sure every change
was reflected in the manuals.)


** Understanding Emacs Internals.

The best way to understand Emacs Internals is to read the code,
but the nodes "Tips" and "GNU Emacs Internals" in the Appendix
of the Emacs Lisp Reference Manual may also help.

The file etc/DEBUG describes how to debug Emacs bugs.



This file is part of GNU Emacs.

GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

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