How to contribute new code or bug fixes

    Using darcs

    This is the preferred option since darcs is the version control system used to manage the source code and wiki of Basilisk.

    If you followed the installation instructions (using darcs), you can easily generate a new patch for the Basilisk main distribution using the following workflow:

    1. cd $BASILISK
    2. Synchronize your repo with the main branch using darcs pull.
    3. Edit the source files.
    4. Test that the changes work: add a test case, run the test suite.
    5. If you created new files, add them to the distribution using darcs add.
    6. Check that your code follows the coding style guidelines.
    7. Review and record the changes using darcs record.
    8. If you are still not happy with your patch, you can go back to 1. and use darcs amend to modify it until your are satistfied.

    Note that, for consistency, the patch title should start with a capital and also be reasonably descriptive. Avoid titles such as “Modified this file”, we (through darcs) already know which files are modified by the patch, rather you should explain concisely what the patch does. Use

    darcs changes | more

    to see examples of patch titles and summary.

    Also for consistency, your identity/authorship should be something like:

    Joe Bloggs <>

    You can change it by editing the $HOME/.darcs/author file.

    You are then ready to submit your patch. You have two options: a simple one (email) and a more systematic one (publishing your repo).

    Emailing your patch(es)

    Just use darcs send -o patches (with a better name than patches) and select which patches you want to submit. Attach the patches file to an email and send it (with some explanations) to the basilisk-fr mailing list.

    Publishing your repository

    You can use a darcs hosting service, such as darcs hub to publish your repository. Note that both the Basilisk wiki and source code are mirrored on darcs hub. To create your own branch, login into darcs hub, go to the basilisk repo and use the fork button.

    Note that if you have ssh/scp access to a web server somewhere, you can also simply copy your repository there.

    To publish your changes, you can then darcs push them to this repository and send its http:// address together with your message to the mailing list.

    Using Unix patches

    If for some reason you don’t want/can’t use darcs, you can simply send a Unix patch to the mailing list. Let’s assume you modified src/fractions.h. You first need to get back to the original version of this file (using the original tarball, getting the raw page source on the wiki etc.) and save it as src/fractions.h.orig, then do:

    cd $BASILISK
    diff -u fractions.h.orig fractions.h > fractions.patch

    You can then review the changes in the patch file and send it to the mailing list if you are happy with it. Note that much more complex patches (for multiple files and directories etc.) can be generated. See the many online tutorials if you want to know more about patching.

    Coding style guidelines

    Before submitting new patches, please check that your code verifies the following conventions:

    1. It is indented properly. You should (must!) use a text editor which does this automatically. The standard indentation is two spaces. This is the default in emacs for example. In emacs you can easily indent/reindent an entire block of code by selecting it (with Ctrl-space or the mouse) and hitting the TAB key.

    2. Lines are not longer than 80 characters. If necessary reformat the code by cutting lines in logical places to make them fit. This is also true of comment/documentation blocks. Note that emacs will automatically reformat long paragraphs of text if you use ESC-q.

    3. Comments starting with “/**" are assumed to be formatted using the wiki markdown syntax. Please respect/use this. They are meant to be written using grammatically/typographically correct sentences i.e. starting with capitals, ending with ., with a subject and a verb, proper spelling etc. This is what literate programming is about.

    4. Check that your code ‘fits in’ stylistically with the existing code i.e. look around and copy what you see!. In particular, the Basilisk convention is to use “natural” punctuation/spaces. For example, commas are always followed by a space and opening and closing parenthesis are preceded (resp. followed) by a space. For readability, the ‘+’ and ‘-’ operators are preceded and followed by a space, but the ’*‘and’/’ operators are not.

    This may seem like nitpicking but think how disagreable it is to read a text which is full of spelling mistakes and/or typographic errors. The same holds for code and, with some discipline (which is also generally useful when programming…) and some training, following the conventions above is not difficult.

    Markdown documentation

    The Basilisk wiki uses pandoc to generate HTML pages from the documented source files. Markdown is a fairly common and quite simple text formatting language. Most of the common text formatting objects are available: headings, bold, italics, lists, tables, figures, code listings etc. A useful extension provided by pandoc is the support for mathematical expressions written in TeX. Have a look at the extensive pandoc Markdown manual for details.

    In addition to what is available in pandoc, Basilisk also provides support for inline plots.

    Generating local HTML pages

    Documented source files included in patches pushed to the wiki will automatically be rendered as HTML. Before pushing a patch, it is important to check that the Markdown documentation is formatted and renders properly in HTML (and also that links to images and other content are not broken etc.).

    A simple, but cumbersome way to do this is to cut-and-paste the entire source file into a temporary page, created using the web interface of the wiki, and use the “Preview” button. Repeat until satisfied and then cut-and-paste from the web interface back into the local file. Then use the “Discard” button.

    A better way to do this is to generate a local HTML file and open it with your web browser. To do this, you first need to install pandoc. If you want to use BiBTeX-style references (see this example), you will also need to install bibtex2html. If you are using a Debian-like system, just do:

    sudo apt-get install pandoc bibtex2html

    As an exercise, we will generate the documentation for a simple test case: Oscillations in a parabolic container. We first run the test case using:

    cd $BASILISK/test
    make parabola.tst

    which should return either

    make: `parabola.tst' is up to date.


    qcc -autolink -g -Wall ... parabola.c -lm
    qcc -autolink -g -Wall ... parabola-explicit.c -lm

    We then generate the corresponding inline plots using:

    make parabola/plots

    Finally, we generate the HTML page using:

    make parabola.c.html

    The HTML file can then be rendered using e.g.

    firefox parabola.c.html

    Once the file is opened in the web browser, one can repeat the steps above and use the “Reload” button of the browser to refresh the rendering. Plugins such as Firefox Auto Reload can also be used to automate this step.

    Emacs Basilisk mode

    If you are using emacs (if not you should!), you can use the Basilisk mode to automate many of the steps above and benefit from a better interface to edit both the C code and Markdown documentation.

    To install it, you will need both mmm-mode and markdown-mode, which are easily installable on Debian-like systems using:

    sudo apt-get install mmm-mode elpa-markdown-mode

    Then add the following to your .emacs (or .emacs.d/init.el) file:

    ;; Use markdown-mode for .page files
    (add-to-list 'auto-mode-alist '("\\.page\\'" . markdown-mode))
    ;; Basilisk mode
    (add-to-list 'load-path "$BASILISK")
    (require 'basilisk-mode)

    where you need to manually replace $BASILISK with the corresponding path.

    Restart emacs and open test/parabola.c. This should use the standard C-mode by default. To switch to Basilisk mode just type

    Esc-x basilisk-mode

    The Mardown-formatted comments should now use a different background color. The emacs mode menus will also change depending on where the cursor is positioned.

    To generate the HTML page and open it in your web browser, just move the cursor within a Markdown comment block and hit F8. To refresh the HTML page hit F9 and use the “Reload” button of your web browser (or the F5 or Ctrl-R keys within the web browser).