Christoph pointed me to a video on Git by Linus.\nCDK is now using branches extensively in development, and just set up a branch for the upcoming 1.2.0 release\nlater this year (end of October, see cdk-1.2.x). Christoph has just\nreviewed\nthe branch containing the API move to Iterable. This patch now\nallows to do this (which would really deserve a blog item by itself):
\n\nfor (IAtom atom : molecule.atoms()) {\n System.out.println(\"Symbol: \" + atom.getSymbol());\n}\nNow, while branching in SVN is easy (svn copy), merging is a pain, something Miguel and I found out in the last half year, where\nhe and I experimented with using branches in development (see also Comparing Branches ).\nWe discovered that porting bug fixes from trunk to a branch, or just keeping the branch synchronized with trunk, simply does not work.\nAnd merging itself, after a while, became a tedious process. So, when watching Linus’ movie on Git where he mentions being able to\nmerge several branches a day, I knew I had to switch. A full switch for the CDK depends\non an always accessible repository (I have been thinking about GitHub; anyone with an opinion on that?).
However, you can start using Git without a central Git repository, including branch support. This blog by\nBart has the juicy details, which I’ll apply here to CDK, for easy\ncopy/pasting. This replaces the earlier writing on\nOffline CDK development using git-svn .
\n\nFirst step is to get yourself a Git mirror of SVN (which will take a long time; do it overnight(s)):
\n\n$ git svn clone https://cdk.svn.sourceforge.net/svnroot/cdk/cdk/ -T trunk -b branches -t tags\n$ git gc\nThe second command compresses commits to reduce the size of your local Git copy, resulting in a cdk folder of about 300MB. Enter the\ndirectory, and check that it has the default master branch:
$ git branch\n* master\nIn SVN one must always do a svn update before one starts coding. Similarly, in git you do (and I found this important to keep your local repository consistent):
\n\n$ git svn rebase\nCommitting has not changed, and a simple change would go via:
\n\n$ nano build.xml\n$ git commit -m \"Changed something, but too lazy to write up what I actually changed\" build.xml\n$ git svn dcommit\nNow, before we move to setting up branches, one must realize that there are SVN branches and (local) Git branches. Keep that in mind, and\nconsider that we have Git to realize how to keep them synchronized. The check the Git branches one uses git branch as shown above; to\nview the SVN branches, however, we type (which should produce a quite long list for the CDK; only a few listed below):
$ git branch -r\n trunk\n tags/cdk-2003-Oct-17\n cdk-1.2.x\n mesprague-iterators\nHere, the first is CDK trunk, the second a tag\ntags/cdk-2003-Oct-17, and the last two are the branches\ncdk-1.2.x and mesprague-iterators (no longer existing).\nI am not sure why the branches/ is missing here; some git-svn magic I presume.
\n\nNow, to create local Git branches that are synchronized with the SVN cdk-1.2.x and cdk-1.0.x branches, we type:
\n\n$ git checkout -b my-local-1.2 cdk-1.2.x\n$ git checkout -b my-local-1.0 cdk-1.0.x\n$ git branch\n* master\n my-local-1.0\n my-local-1.2\nYou can now easily change branches with git checkout <BRANCH>, and check which SVN path you are working against with git log -1:
$ git checkout my-local-1.2\n$ git log -1\ncommit 93bd0b22bbad31897eed6686e5b208c5e23505f7\nAuthor: egonw\nDate: Sun Sep 7 08:13:38 2008 +0000\n\n Fixed inline citation (closes #1987947)\n\n\n git-svn-id: https://cdk.svn.sourceforge.net/svnroot/cdk/cdk/branches/cdk-1.2.x@12215 eb4e18e3-b210-0410-a6ab-dec725e4b171\nInspection of the output shows the git-svn-id line which indicates that that patch was indeed commited against cdk/branches/cdk-1.2.x.
With this set up, I can easily changes between trunk and branches, and backport patches from trunk to the cdk-1.2.x\nbranch (using git cherry-pick) and merge all commits to the branch into trunk using:
$ git checkout master\ngit merge cdk-1.2.x\nGit does an excellent job here. It recognizes when the branch was last merged with trunk, and will not attempt to apply\npatches twice. Even better, it also recognized patches that were backported from trunk to the branch, and will not attempt\nto merge that either.
\n\nThe result: I can easily merge branches now, generally speeding up CDK development! For example, it reduces the time\nbetween someone submits a patch, and when I apply it to trunk (or cdk-1.2.x in case of a bug fix). I just set up a\nlocal branch, apply the patch, and tune until I am happy; I do not keep trunk unstable, as I am doing this in a\nseparate branch. Similarly, if people develop there patch in an SVN branch, I can just as easily switch branches\n(as described above) and check things, before I merge).
\n\nAs far as I know, git-svn cannot create or delete new SVN branches. But this is easy enough with SVN command:
$ svn copy https://cdk.svn.sourceforge.net/svnroot/cdk/cdk/trunk https://cdk.svn.sourceforge.net/svnroot/cdk/cdk/branches/egonw-mynewbranch\n$ git svn fetch\n$ git checkout -b my-local-newbranch egonw-mynewbranch\n$ # hack in my-local-newbranch\n$ git commit -a\n$ git svn dcommit\n$ git checkout master\n$ git merge my-local-newbranch\n$ svn remove https://cdk.svn.sourceforge.net/svnroot/cdk/cdk/branches/egonw-mynewbranch\nEnough for now.
", "summary": "Christoph pointed me to a video on Git by Linus. CDK is now using branches extensively in development, and just set up a branch for the upcoming 1.2.0 release later this year (end of October, see cdk-1.2.x). Christoph has just reviewed the branch containing the API move to Iterable. This patch now allows to do this (which would really deserve a blog item by itself):", "date_published": "2008-09-07T00:00:00+00:00", "date_modified": "2025-10-11T00:00:00+00:00", "tags": ["cdk","svn"], "authors": [ { "name": "Egon Willighagen", "url": "https://orcid.org/0000-0001-7542-0286" } ] } ] }