How to create a patch

If you have made some changes to the code that you would like to share with the community, particularly if you want to send them to one of the core developers for possible inclusion in Moodle Core, it is very helpful if you can provide them as a patch file. Sometimes also called a diff file.

This page explains how you can make a patch file. Patch is a standard format, and there are many options for how to create one. Pick the one that is easiest for you. One of the most critical aspects of patch usage is identifying for your audience the location for the patch file for application relative to the -p flag! When you create patches note your location and provide that when you share patches.

Note, I have not been able to test most of these instructions. They are about right, but I am hoping that as people use them, they will fill in any gaps, correct any details, and so on.Tim Hunt 08:40, 25 June 2007 (CDT)

Creating a patch using diff

diff is the a linux command line program, and is where patch files originated. It requires that you have two copies of the code, one with your changes, and one without. Suppose these two copies are in folders called 'standard_moodle' and 'my_moodle' which are subdirectories of the current folder. Then to create the patch, type:

diff -Naur standard_moodle my_moodle > patch.txt

Creating a patch using CVS (command line)

It is easier if you are using CVS to manage your development, because you don't need to keep the copy of 'standard_moodle'. CVS takes care of that for you. In your workspace (sandbox) type:

cvs diff -uN > patch.txt

If you have unversioned files to include in your patch, you will notice that the above command simply adds the file's name to the top of your patch, prefixed with a question mark. This is because your new file is not tagged for adding to the repository. Just do

cvs add newfile

Then

cvs diff -uNa > patch.txt

This should add the correct code to the patch, so that someone applying the patch to their working copy will have a new file created at the right place (hopefully!).

If your patch, for some reason, contains a lot of white space changes in many files, you might want to add -Bbw to the diff call. Make sure these changes are really not significant (like adding or removing a space at the end of a line - editors like Eclipse sometimes do this automatically). This can make a patch a lot smaller, and thus easier to review. The complete call would then be

cvs diff -uNawbB > patch.txt

Creating a patch using Tortoise CVS

Tortoise CVS is a Windows GUI front end for CVS. To create a patch, right-click on a folder in CVS, and choose CVS -> Make patch ... from the context menu.

Creating a patch using Eclipse

See Setting_up_Eclipse#Creating_a_patch. Eclipse makes creating patches really easy, once you have got it set up correctly.

Creating a patch using WinMerge

WinMerge is a nice windows GUI for comparing folders. In this sense it is like the original command-line 'diff' program. You need a copy of 'standard_moodle' and 'my_moodle'. Use File -> Open... to open the two versions for comparison. This will give you a nice view of what you have changed. Then do Tools -> Generate patch .... In the dialogue box, make sure you select Style: Unified in the Format box.

Creating a patch using Git

Creating a patch if you're using Git for version control is similar to CVS, and similarly you don't need an unchanged copy of moodle to diff against. The easiest way to create a patch for the last commit is

git show > patch.txt

or if you want to create a patch between 2 specific commits you can use git diff

git diff commitid1 commitid2 > patch.txt

There's also a tool, format-patch, for formatting a patch to send as an e-mail. You can create patches for the last n revisions like this:

git format-patch -n

which will create the patch in the current directory. The -o parameter allows you to specify a different output directory.

See Also

• How_to_apply_a_patch
• Patch