]> snarfed.org draw group stream of consciousness Ryan Barrett <snarfed at ryanb dot org> en text/html Copyright 2002-2007 Ryan Barrett fillcode Ryan Barrett <snarfed at ryanb dot org> 2003-01-01T05:00:00Z en text/html Copyright 2002-2007 Ryan Barrett

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For the impatient:
  Download fillcode.el 0.7.1
  Download fillcode.tar.gz (includes elunit unit tests)

Updated 2007/08/24.

Fillcode is an Emacs minor mode that fills, or wraps, some parts of source code. It's best described by example. Fillcode fills this:

public static void foo(int i, float f, String s) {


to this:

public static void foo(int i, float f,
                       String s) {


The motivation is described in my original call for filling code.

Fillcode can fill any parenthesized expression, including function prototypes, function calls, and conditional expressions. It only breaks lines at commas and binary operators, and correctly preserves embedded comments and string literals. It also normalizes existing whitespace and line breaks.

Fillcode is supported in Emacs 21 and 22 and XEmacs, and works with most programming language major modes, including Java, C, C++, Objective C, Perl, Python, shell, and SQL modes.

Fillcode fills when fill-paragraph (usually M-q) is called. If the major mode itself attempts to fill - inside a comment, for example - fillcode graciously steps back and does nothing.

If you provide a prefix argument, e.g. C-u M-q, fillcode will automatically insert a line break at the first open parenthesis or other appropriate point. This can be useful when the first open parenthesis is near fill-column.

You can load fillcode automatically by copying fillcode.el into /usr/share/emacs/site-lisp/, or any other directory in Emacs' load-path. Then, add this to your .emacs file:

(require 'fillcode)


M-x fillcode-mode toggles fillcode on and off in the current buffer. To turn it on automatically whenever you open source code, add these lines to your .emacs file.

(add-hook 'c-mode-common-hook 'fillcode-mode)
(add-hook 'perl-mode-hook 'fillcode-mode)
(add-hook 'python-mode-hook 'fillcode-mode)
(add-hook 'shell-script-mode-hook 'fillcode-mode)
(add-hook 'sql-mode-hook 'fillcode-mode)


Fillcode is a work in progress. Here's a list of issues:

  • It depends on the major mode's indentation and parsing engines. These are less than perfect in some major modes.
  • It's not entirely compatible with auto-fill-mode or filladapt-mode...yet.
  • It doesn't break lines at =, the assignment operator.

Fillcode is copyright 2005-2007 Ryan Barrett, and is distributed under the GPL.

 http://snarfed.org/ fillcode-1 hober cmt_pubDate text/html FYI, fillcode.el doesn't work with the python.el in CVS Emacs. http://snarfed.org/ fillcode-2 ryan cmt_pubDate text/html thanks for the feedback! ay, really, it doesn't? i've been testing with python-mode 4.6.18.2, and it works ok.

would you mind describing in more detail what doesn't work with the python-mode in CVS? http://snarfed.org/ fillcode-3 ryan cmt_pubDate text/html in python-mode, one problem with the original fillcode i posted was that it often filled more than just the single statement under point. i've posted a new version that is much better (and thus more polite) about determining where the current statement ends.

thanks for the bug report! http://snarfed.org/ fillcode-4 hober cmt_pubDate text/html <pre>Debugger entered--Lisp error: (void-function py-in-literal) py-in-literal() funcall(py-in-literal) (or (funcall in-literal-fn) (eval (cons … ...))) (let ((in-literal-fn ...) (literal-start-tokens ...)) (or (funcall in-literal-fn) (eval ...))) fillcode-in-literal() (cond ((fillcode-in-literal) (forward-char)) ((eolp) (delete-indentation t)) ((looking-at ...) (delete-horizontal-space) (if … ...)) ((and … ...) (progn … ...)) ((and … ... ...) (progn … ...)) (t (forward-char))) fillcode-collapse-whitespace-forward() fillcode() call-interactively(fillcode) execute-extended-command(nil) call-interactively(execute-extended-command)</pre> http://snarfed.org/ fillcode-5 hober cmt_pubDate text/html (python.el in CVS Emacs is completely different than python-mode.el from python.org.) http://snarfed.org/ fillcode-6 ryan cmt_pubDate text/html yeah, i do remember that. sigh. thanks for the info.

i just downloaded and built CVS emacs, and it breaks the fillcode unit tests spectacularly. that'll be a good place for me to start. http://snarfed.org/ fillcode-7 ashawley cmt_pubDate text/html Rather than defining a mode and using hooks you can just set `fill-paragraph-function' to the desired "fillcode" function. See the command help on `fill-paragraph' at `C-h f fill-paragraph'. http://snarfed.org/ fillcode-8 ryan cmt_pubDate text/html good point. that's true for all major modes that respect `fill-paragraph-function'.

unfortunately, cc-mode doesn't. it replaces `fill-paragraph' with `c-fill-paragraph', which it binds M-q to. `c-fill-paragraph' ignores `fill-paragraph-function' entirely. :/

so, for fillcode to work in cc-mode major modes, it has to do something like advise `c-fill-paragraph'...which it does. still, you're probably right, it doesn't need a whole minor mode. i'll consider removing that in the future. http://snarfed.org/ fillcode MartinG cmt_pubDate text/html Thanks for this very nice emacs mode!

I think I found one bug though - when filling this string:
  <code>for (iy = 0; iy < dLy; iy++)</code>
it becomes
  <code>for (iy = 0; iy < dLy; iy+ +)</code>
i.e. it separates the "+" signs. This is in cc-mode. http://snarfed.org/ fillcode Vomicae cmt_pubDate text/html Fillcode is Perl the best http://snarfed.org/ fillcode ryan cmt_pubDate text/html thanks for the report, martin. a fix for that went in in 0.5 or 0.6. sorry for the delayed response!