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Version control and outside contributors

The version control system your project uses can have a big impact on how easy it is for outside contributors to help out.

Svn (and cvs) make it difficult to contribute

Most projects restrict new or minor contributors to read only permission on their code repositories. This is common both for security and for organizational purposes, project maintainers often like to review changes before they go into mainline code. Read only access has its downside for contributors. If someone like myself wanted to contribute to a project that used svn the flow wold look something like:

- svn checkout
- Edit files in my editor
- Test
- svn diff > changes.patch
- Email/post changes to maintainer
- Wait until the changes are approved or rejected and checked in to svn
- Repeat starting at 'Edit files in my editor'

The bottleneck here is waiting for changes to be checked into svn. What if there were several changes in series? How would I be able to continue working on the next change if one change was already pending? What if the project maintainer(s) took a week to approve/reject or check in the changes?

Svn's centralized design is extremely constraining to rapid development and experimentation.

Making things easier with decentralized version control

Git and other decentralized version control systems solve the issues mentioned above. Git, for instance, enables users to check in any number of changes as well as create branches freely.

What if you want to use git but the project you'd like to contribute to is using svn? Github is a great resource that can help. They provide free hosting and have a helpful page about how to import a svn project into git.

Recently I wanted to start contributing to EmbSysRegView but the project is still using svn. I've been using git for several years now and at my full-time job for a year or two since I was able to convince the team to migrate from svn. I'd prefer to work in git because I could make several changes without having to wait for the maintainers. Plus git is a much faster tool.

It might be possible to convince the maintainer(s) to switch to git but this can be a bit of a learning process for them and other contributors. It turns out that patch files from git commits can be made compatible with svn in most cases. Git also has support for interacting with svn repositories natively. You can both import changes from svn as they are made and push changes back to svn repositories from git commits.

I decided to go this route and use github to host an import of the EmbSysRegView svn project. It took a few minutes but I was able to import the entire project including its history, tags etc, into a github project.


EmbSysRegView on github
Now that the project is in git it should be easy for me to make a series of changes, submit them as patches to the EmbSysRegView maintainers, and easily rewrite patches from their feedback.



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