Source code management

Our main source code management tool is git. This article explains how to use it and how some general rules apply in the case of FreeCAD. You are highly advised to learn how git works first (there are a lot of tutorials and docs available for git on the internet) before working with the FreeCAD source code.

There are also many good graphical clients to git, such as git-cola, that make the whole process of managing git repositories easier. FYI there also exists a cursory intro to Developing FreeCAD with GitKraken.

Source Code Access

Everybody can access and get a copy of the FreeCAD source code, but only the FreeCAD project managers have write access to it. You can get a copy of the code, study it and modify it as you wish, but if you make a change that you wish to see included in the official source code, you need to ask for a pull request on the pull requests section of the FreeCAD forum.

NOTE

In all examples below, "GITHUB_USERNAME" represents your GitHub user account.

Official GitHub Repo

An easy way to start with the FreeCAD source code is using the official FreeCAD repository at https://github.com/FreeCAD/FreeCAD

Setting your git username

Users should commit to their project repository using their GitHub username. If that is not already set globally, you can set it locally for the current Git repository like this:

git config user.name "YOUR NAME"
git config user.email "GITHUB_USERNAME@users.noreply.github.com"

You can now use some combination of "git add" and "git commit" commands to create one or more commits in your local repository.

A note about Remotes

Please read some background to help you understand better the difference between what origin and upstream mean in the context of git. This section explains how to set the correct upstream and origin remote git repos. Essentially:

• origin = Your fork of the FreeCAD git repo AKA https://github.com/GITHUB_USERNAME/FreeCAD.git
• upstream = The official FreeCAD git repo AKA https://github.com/FreeCAD/FreeCAD.git

  This is important to understand because if you git clone directly from upstream then confusingly, your origin will be listed as https://github.com/FreeCAD/FreeCAD.git
  BTW, if you do this accidentally you can use the git remote rename command to remedy the situation.

So, based on the above, there are 2 main ways to setup your git environment:

• 1st Method: Fork on GitHub and clone your fork locally
• 2nd Method: Clone FreeCAD official directly to your local machine

We recommend the 1st method for the reason mentioned above.

1st Method: Fork on GitHub and clone your fork locally

Important Note

You will need to re-configure 'remote upstream' as mentioned above in "A note about Remotes"

This method is the recommended way since it takes less steps. You will essentially fork the FreeCAD repo on your own GitHub account and then clone said GitHub fork locally. Then you will set your upstream repo in git. The procedure is as follows:

1. Sign up for a GitHub account if you don't already have one
2. Go to the FreeCAD repo: https://github.com/FreeCAD/FreeCAD
3. In the top right of the page find and press the "Fork" button (this will essentially git clone the official FreeCAD repo to your personal GitHub repo: https://github.com/GITHUB_USERNAME/FreeCAD.git)
4. On your machine, clone your newly created FreeCAD fork by opening a terminal and typing:

   git clone https://github.com/GITHUB_USERNAME/FreeCAD.git

5. Once the clone process is complete, now set your upstream remote repo (see "A note about Remotes"). Find out what and where your remote git repositories are set to. Type git remote -v and the output should look similar to:

    [foo@bar FreeCAD]$ git remote -v
        origin	https://github.com/GITHUB_USERNAME/FreeCAD.git (fetch)
        origin	https://github.com/GITHUB_USERNAME/FreeCAD.git (push)

6. Great. Now set your upstream repo

   [foo@bar FreeCAD]$ git remote add upstream https://github.com/FreeCAD/FreeCAD.git

7. Check your remotes again, they should look similiar to this:

    [foo@bar FreeCAD]$ git remote -v
       origin	https://github.com/GITHUB_USERNAME/FreeCAD.git (fetch)
       origin	https://github.com/GITHUB_USERNAME/FreeCAD.git (push)
       upstream	https://github.com/FreeCAD/FreeCAD.git (fetch)
       upstream	https://github.com/FreeCAD/FreeCAD.git (push)

8. Now we can start developing. Please refer to "Git Development Process"

2nd Method: Clone Official FreeCAD git repo to your local machine

Important Note

You will need to re-configure both 'remote origin' and 'remote upstream' please refer to above "A note about Remotes"

This method of setuping your git environment takes a few more steps then the 1st method. You will clone the FC git repo directly to your local machine and then alter your remotes via the terminal. The procedure is as follows:

1. Clone the FreeCAD code with git:

   git clone https://github.com/FreeCAD/FreeCAD.git

2. Create an account on a public git server (GitHub, GitLab, etc... for our purposes we're assuming it's GitHub)
3. Find out what and where your remote git repositories are set to:

   git remote -v

4. This will return something that looks like the following:

   [foo@bar FreeCAD]$ git remote -v
       origin https://github.com/FreeCAD/FreeCAD.git (fetch)
       origin https://github.com/FreeCAD/FreeCAD.git (push)

5. As was explained above in "A note about Remotes" you need to modify these remote git repo addresses.
   So first set up your origin remote:

   [foo@bar FreeCAD]$ git remote add origin https://github.com/GITHUB_USERNAME/FreeCAD.git

6. Then we set up our upstream remote:

   [foo@bar FreeCAD]$ git remote add upstream https://github.com/FreeCAD/FreeCAD.git

7. Check your remotes again, they should look similiar to this:

    [foo@bar FreeCAD]$ git remote -v
       origin	https://github.com/GITHUB_USERNAME/FreeCAD.git (fetch)
       origin	https://github.com/GITHUB_USERNAME/FreeCAD.git (push)
       upstream	https://github.com/FreeCAD/FreeCAD.git (fetch)
       upstream	https://github.com/FreeCAD/FreeCAD.git (push)

8. Now we can start developing. Please refer to "Git Development Process"

Git Development Process

First of all NEVER DEVELOP ON THE master BRANCH! Instead, create a local branch for development. You can learn in more depth by reading Git-Branching-Basic-Branching-and-Merging chapter on git-scm. Below is a summary:

Branching

An important feature of Git is that it is extremely easy to work with branches and merge them together. Best practices recommend to create a new branch whenever you want to work on a new feature. Creating a branch is done with:

git branch myNewBranch
git checkout myNewBranch

or you can combine both git branch && git checkout together by using the -b flag

git checkout -b myNewBranch

How do you know which branch you are currently using? Easy, type:

git branch

Committing

Once you did some work, you commit them with:

git commit -a

Unlike SVN, you need to specifically tell which files to commit (or all with the -a option). Your text editor will open to allow you to write a commit message.
Please read more about Writing good commit messages in the below section.

Publishing your work on your GitHub repository

Important Note

If you have code you wish to see merged into the FreeCAD source code, please post a note in the Pull Request section of the FreeCAD forum

After you're correctly branched made some modifications to your local branch and commit them 'locally', you can push your repository to your remote git server (in this example we're assuming GitHub). This opens your branch to the public and allows the main developers to review and integrate your branch into master.

git push <REMOTENAME> <BRANCHNAME> 
git push origin my-branch

For further info on this subject please read https://help.github.com/articles/pushing-to-a-remote/

Writing good commit messages

You should try to work in small chunks. If you cannot summarize your changes in one sentence, then it has probably been too long since you have made a commit. It is also important that you have helpful and useful descriptions of your work. For commit messages, FreeCAD has adopted a format mentioned in book Pro Git (see #Further Reading).

Short (50 chars or less) summary of changes

More detailed explanatory text, if necessary.  Wrap it to about 72
characters or so.  In some contexts, the first line is treated as the
subject of an email and the rest of the text as the body.  The blank
line separating the summary from the body is critical (unless you omit
the body entirely); tools like rebase can get confused if you run the
two together.

Further paragraphs come after blank lines. 

 - Bullet points are okay, too

 - Typically a hyphen or asterisk is used for the bullet, preceded by a
   single space, with blank lines in between, but conventions vary here

If you are doing a lot of related work, it has been suggested here that one should make as many commits large or small as makes sense for what you are working on using the short one sentence commit messages. When you want to merge, do a

git log master..BRANCH

and use the output as a basis for your quality commit message. Then when you merge to master use the --squash option and commit with your quality commit message. This will allow you to be very liberal with your commits and help to provide a good level of detail in commit messages without so many distinct descriptions.

Advanced git operations

Check out GitHub Requests Locally

https://gist.github.com/piscisaureus/3342247

Resolving Merge Conflicts

• git-scm explanation on how conflicts are presented
• GitHub article on resolving merge conflicts via the command-line
• Customize your preferred merge tool when you encounter a git conflict.

Applying patches via git

Git has the capability to merge patches/diffs. To read more about this read the following reference: https://www.drupal.org/node/1399218

git apply [patch-name].patch

Apply a patch via curl

A very handy and powerful feature of git and the command line is the ability to quickly test patches all through the terminal.

curl -O https://github.com/FreeCAD/FreeCAD/commit/[patch-name].patch
git apply [patch-name].patch

or alternatively, using bash pipes you can make a sweet 1-liner:

curl https://github.com/FreeCAD/FreeCAD/commit/c476589652a0f67b544735740e20ff702e8d0621.patch | git apply -

• Useful tip: Just add .diff or .patch at the end of the URL for a GitHub commit page, Pull Request, or Compare View and it'll show you theplaintext view of that page. Example:

Regular GitHub page: https://github.com/FreeCAD/FreeCAD/commit/c476589652a0f67b544735740e20ff702e8d0621

'Diffed' GitHub page: https://github.com/FreeCAD/FreeCAD/commit/c476589652a0f67b544735740e20ff702e8d0621.diff

'Patched' GitHub page: https://github.com/FreeCAD/FreeCAD/commit/c476589652a0f67b544735740e20ff702e8d0621.patch

Creating patches from git

There are times when one may need to create a patch instead of submitting a PR. The following workflow explains how to do this:

1. Make sure you are in the correct branch (i.e. not the master branch) by checking with

   git branch -v

2. Create the patch: we do this by using the git format-patch command which we patch against the master branch and redirect to STDOUT. We create the patch in the directory outside of the source build (in order not to pollute the source dir itself, this is optional as you can decide the location wherever you want the patch to be created)

   git format-patch master --stdout > ../patch.name.patch

3. Another method is to use git format-patch HEAD^ or git format-patch HEAD~1 The ^ or 1 can be changed to number of commits that should be covered i.e.: ^^^ or ~3.

   git format-patch HEAD^

It will create a patch or series of patches with file name format XXXX-commit-message.patch. An example: 0001-fix-ViewProjMatrix-getProjectionMatrix.patch

Reversing a patch in git

If you've followed the instructions above and then have a change of heart about using the patch, you can quickly reverse it using:

git apply -R path/file.patch

or another way is to use:

git checkout -f

which will remove non-committed changes to the branch

Stashing git commits

Say you're working on a branch and you find yourself making some modification to the source that is out of the scope of your current branch in other words it would be better to add certain commits to a whole other branch and submit it instead of the current one. This is where the git stash command can be very useful. The git stash command can help you to (temporarily but safely) store your uncommitted local changes.

git stash

Then in the future when you want to use these commits you can

git stash apply 

or

git stash pop

pop will delete the stash If you have multiple stashes you can

git stash list

To read more about what other functions you can use checkout https://medium.freecodecamp.org/useful-tricks-you-might-not-know-about-git-stash-e8a9490f0a1a

What is the latest FreeCAD Dev Revision

There are 2 ways to do this:

• 1st method: In your cloned git directory type:

git rev-list --count master

• 2nd method: Browse https://github.com/FreeCAD/FreeCAD and read the amount of commits FreeCAD is at.

What is the Revision number of a specific commit hash and visa ver?

git rev-list --count 9948ee4
13541

• some forum topics in this regard:
  • https://forum.freecadweb.org/viewtopic.php?f=10&t=26673
  • https://forum.freecadweb.org/viewtopic.php?t=5308
  • https://forum.freecadweb.org/viewtopic.php?f=18&t=12883&p=103207#p103203
  • https://forum.freecadweb.org/viewtopic.php?f=10&t=31118

How is the Revision number in FreeCAD help about generated?

• https://forum.freecadweb.org/viewtopic.php?f=4&t=3025

Alternative repositories

The beauty of git is that everybody can clone a project, and start modifying the code. Several frequent collaborators of the FreeCAD project have their own git repository, where they build up their work before it is ready to be included in the official source code, or simply where they experiment new ideas. In certain cases, you might want to clone your FreeCAD code from one of these, instead of the official repos, to benefit from the changes their users did.

Be warned, though, that this is at your own risk, and only the official repository above is fully guaranteed to work and contain clean code.

It is also possible to attach several remote repositories to a same local FreeCAD git code, using the "git remote" command. This is useful to keep in sync with the master code branch, but keep an eye on the work of different developers.

Using git in a Graphical User Interface

• Developing FreeCAD with GitKraken

Further reading

• Git for the lazy
• The entire Pro Git book