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How to Submit Patches

User contributions and especially patches are very important for Cafu. Patches help us to add new features, improve code quality and fix bugs, so we are happy if you contribute them (how could we dislike your help, after all?). :-)

However, we have all sort of problems with applying non-standard patches. To make life easier for both you and us, please follow the few simple rules below when submitting patches.

Remember that if you have any questions about the steps here, you can always post them to the Cafu forum and we'll do our best to help you.

Changing Cafu

Follow the rules

Read the Coding Conventions and try to conform to them. In particular, please respect the indentation rules (4 spaces, no TABs) – patches are really difficult to read otherwise.

Provide documentation

Bug fixes and elegant program solutions often involve complex code that can be difficult to understand without documentation, and an undocumented new feature is hardly useful to anyone but its author.

Therefore, please provide any required documentation such as source code comments (preferably in familiar and simple Doxygen format), high-level overviews, diagrams, etc. Without documentation, another developer would have to write it, and the patch cannot be applied until he has time to do it.

Mechanics of Patch Submission

Use the latest version

Always make your patches against the latest version of Cafu.

In most of the cases, you should make a patch against the head revision of the SVN trunk. You can learn how to download the source code from the Subversion repository here.

If you cannot access the Subversion repository (for example when you are behind a firewall), make the patch against the latest source code release at the Downloads page.

Standard patch format

A patch is a single file that contains the differences in all files that you modified. Patch files are small, easy to read and understand and can be applied with a single command, even if the affected files have been changed since the moment when the patch was created.

Therefore, do not send us ZIP archives, whole files, code snippets or other arbitrary text that we'd spend hours trying to understand.

There are several ways to create patches:

  • Use TortoiseSVN or a similar GUI client for Subversion. TortoiseSVN integrates into the Windows explorer and can create patches comfortably from the right-click context menu. It also allows you to select the individual files that should or shouldn't be included in the patch. Thus we recommend that you use TortoiseSVN, especially if you don't feel comfortable with svn diff at the command-line.
  • Also straightforward and easy is the use of svn diff at the command-line:
    svn diff > mypatch.patch

    Similar to TortoiseSVN, if your patch adds or removes files, you should run svn add or svn remove before svn diff.

  • If you don't use Subversion at all, you can use the diff program which is a standard part of most Unix systems and is available as part of the Cygwin package or elsewhere for Windows:
    diff -uNr Cafu-src-orig Cafu-src-mine > mypatch.patch

    Use the -u option for unified diff output and -N for the new files to be included in the patch.

Standard patch file extensions

Use standard extension .diff or .patch for the patch file.

Omit auto-generated files

Don't include auto-generated files (log files, temporary scripts, etc.) in the patch.

The simplest way to handle this is to use TortoiseSVN, which allows you to select which files should and which files shouldn't be included in the patch. Alternatively, it is also easy to edit the patch to remove appropriate chunks.

Make atomic patches

Do not split single code change into multiple patches. A patch should be self-contained – one patch for one thing.

A patch that adds bitmaps to menu items and fixes a bug in the network code is a bad patch. It should be splitted into two patches. On the other hand, two patches, one of them being “implementation of new member-functions”, the other “changes in class description to accommodate new members” are two bad patches. They are related to one, logically indivisible, thing, so they should be part of one patch.

Another example: if you adapted the build system to work on new, previously unsupported platform, we would gladly accept your patch. Just send us single patch, not 10 patches, one for each modified file.

Submitting the Patch

Use Trac

Please do not send the patches to the forum, mailing list, or to any developer's personal email address. Instead, use the issue tracker. Then you will be notified about the progress the patch makes, e.g. when the patch is accepted or if there is a problem with applying the patch.

Describe your changes

Please fill in the ticket form as explained at SubmitTickets.

Remember that it is often not easy to understand the purpose of your patch just from its source code. If you provide detailed description of the patch, we will be able to apply it much faster – and we will love you for submitting such nice patches! :-D

Let us know your name

We'd also like to give you credit for your patch (unless it's something really trivial as we avoid mentioning very small changes in our changelog) but we need to know your real name for this. Please tell us if we don't know you already e.g. from the forum.


  • Attach a unified diff against the SVN trunk to a ticket in the issue tracker.
  • Remember to add any relevant information or docs.

Thank you for reading this document – we're looking forward to your patches!

cppdev/submitpatches.1262789096.txt.gz · Last modified: 2013-01-07 12:07 (external edit)