If, like me you were a heavy piston user, you are wondering how you will be able to do the same thing if you switch to git.

First off, you need to know that Piston will soon support git. As a matter a fact it already does. At least you can download a beta version from François’s blog.

You can also go with giston/braids which was meant to make the svn/switch easy on you. I heard rumors that evilchelu might not keep on developing this project. You might want to check with him.

Personally I didn’t really like using any of these solutions. Rails also came with its’ own approach. (rake rails:freeze:edge)

When I recently worked on Merb’s freezer, I discovered the power of git submodules.

Submodules allow you to import “modules” from other git repos inside your own repo. Basically they do what piston does for SVN, apart that submodules are built-in git. Of course it has an expected limitation, you can only add git submodules.

The good news is that Rails moved to git and now you can “freeze” Rails as a submodule and update really easily!

First thing first, you need to move your project to git. If you are not confident it’s a good move yet, you can use “git-svn”. However, I would personally recommend you don’t. I did that for few months and when I finally moved to git only, it was a pain to restructure the entire path of the app.

Anyways, let’s say you created a new github project and if still wish to use git svn do:

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$ git-svn import svn://path-to-your-svn-repo project-name
$ cd project-name
$ git remote add origin git@github.com:mattetti/project-name.git
$ git push origin master

Your project is now under git, but if you pistonized Rails, you can’t update it anymore

Do not fear my dear friend and do as follows:

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$ rm -rf vendor/rails
$ git commit
$ git submodule add git://github.com/rails/rails.git vendor/rails
$ git submodule init
$ git commit
$ 

That’s it you are done

Next time you want to update just do:

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$ cd vendor/rails
$ git remote update
$ git merge origin/master

or you can also do

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$ cd vendor/rails
$ git pull

(yes, each plugin acts a a normal git repo)

A quick note for gitHub users. If you browse your repo you won’t see the vendor/rails folder and might freak out. Don’t! Git is smart and wants to stay slim, instead of copying the files over, it just creates a reference to the original repo. If you try to pull your project in another folder you will see that the Rails folder gets created as expected.

Personally, when plugins are not available in a git repo I usually do a simple svn export to my project vendor’s folder. If I need to modify one of these plugins, I just import it to github and work on it from there.

You might still want to stick to Piston or Braids and that’s fine, but now you won’t have an excuse not to switch to Git

UPDATE: I just found out that Graeme wrote a nice detailed post about tracking plugins using git, check it out

Here is my GitHub account.

Projects moved to GitHub:

• GlobaLite

• ActiveRecord Backup

• mimetype-fu

I’m planning on moving GoogleCharts, RandomWordGenerator and some not released stuff to GitHub so people can have fun forking my projects.

Git and GitHub are the new cool things. GitHub is planning on setting up a gem server while they are already offering tarball download and a post-receive hook. (they also plan on becoming myspace for geeks, but that’s another story)

Do you have to switch to git and github? Honestly, …no you don’t..
Git can act as SVN, but let’s be honest, if you switch to a new SCM it needs to do more. I’ve been using Git for a couple of months and even though I still don’t have a full understanding of this SCM, I really enjoy using it.

So, get over it, learn on your own or purchase this excellent peepcode

Email me to get a GitHub invite (Tom and Chris gave me some invites for readers) or/and try Gitorious.

The fact that some major players (Topfunky, technoweenie, Chris & PJ, jnunemaker and major projects such as capistrano, vlad the deployer and Merb use and support Git is a sign that it’s the next big thing.

Also, I believe that a lot of developers will also be motivated to move their plugins/gems to GitHub because they simply can’t always maintain their own libs and/or just hope people will fork their project and contribute back.

Github is used by the Merb core team and I’ll show you how to use github to fork Merb, make your modifications and “submit your patch”.

This is the exact reason why github is simply awesome, it makes forking projects just super simple and submitting changes even easier.

First thing, you need to have a github account, if you don’t have one yet, email me, I have a couple of invitations left, otherwise, just wait until github gets public.

Now, let’s go to Merb’s repository and fork Merb-core by clicking on the fork button.

Actually, for this example, I’ll fork merb-plugins because I want to improve the ActiveRecord rake tasks.

Because I forked merb-plugins, I now have my own forked repo: !

I’ll start by checking out/cloning my forked repo locally.

git clone git@github.com:mattetti/merb-plugins.git

!

Great I can now make my own changes…. but wait, what if the merb core team makes a change to the code? Well, I need to track their changes. Here is how:

git remote add coreteam git://github.com/wycats/merb-plugins.git

FYI, it adds the following to edit .git/config:

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  [remote "coreteam"]
  url = git://github.com/wycats/merb-plugins.git
  fetch = +refs/heads/*:refs/remotes/coreteam/*

then

git fetch coreteam

and finally

git checkout -b coreteam coreteam/master

You can now track the latest change and merge them with your branch. Note that you can also track other forks and merge some other changes. (just that feature is worth using git)

Alright, now you can do your stuff, and push your local change to your remote repo at github.

Once you are done, you can simply click on the “pull request button”

fill up the form and select the recipient. (wycats in this example if you want him to merge your changes into the official version of Merb).

p.s: The github guys are working on a gem to make our loves easier, give http://github.com/defunkt/github-gem/tree/master a try. I’ll post about the gem when it will be a bit more stable.

On one of my project, we have a SVN repo but since I prefer using Git, I’m using git-svn.

Git-svn has been great, it let me create my own local branches for each new set of features (that’s when I don’t forget to create a branch) and to commit all the changes back to svn.

The problem today happened after I did a simple git-svn rebase. I had some sort of error and my local repo looked like it got reverted to the head of the svn repo….

error: patch failed: trunk/app/models/view.rb:1
error: trunk/app/models/view.rb: patch does not apply
[blah blah]
sing index info to reconstruct a base tree...
Falling back to patching base and 3-way merge...

I hadn’t committed to SVN for 24 hours and had a lot of work that was just checked in locally… You can imagine the panic. Rob started digging in the .git repo to finally find the hash representing the latest delta before the rebase. With the help of the #caboose guys, I did a simple

git reset --hard hash-name

Which restore my repo to the pre SVN commit state. Awesome… however I still had issues to commit my stuff. After a little while I as able to commit again, worked a bit more and tried to commit again…. same error

But this time I noticed I could simply do

git rebase --abort

to restore the original branch.an

But I still couldn’t commit properly… until I discovered that I just needed to fix the conflicts manually using

git-mergetool

git-mergetool uses whichever merge tool available: kdiff3 tkdiff xxdiff meld gvimdiff opendiff emerge vimdiff filemerge

I fixed my conflicts in no time, then did a

git rebase --continue

and finally

git-svn dcommit

Looking back, I wish I knew how to properly deal with conflicts when using git-svn, I wasted a bit of my precious time hopefully this post will help you.

p.s: here is an interesting use of Sake to handle git-svn