Archive for April, 2009

SVN branching

April 29th, 2009 1 comment

I’ll preface this post by mentioning that the steps for branching are already out there on the web. I’m more concerned here with the complexities in setting up a branch in SVN, and then move onto showing how to do the same thing in git. Branching discussed on other sites:
- svn book
- stackoverflow “How do I create a branch in SVN”

The actual command looks as such:
svn copy

As you’ll notice if you look at the subversion command above, the action of branching is not really a staple of subversion. Essentially you’re taking the codebase as of a certain version, copying the entire trunk and placing it in a new home to work with. This process can be quite aggravating, and unless necessary I really try avoiding it.

At a TechTalk on git, Linus Torvalds actually talks at length about this:

If you do brave the current in SVN, just keep in mind that the longer you’re branch is disconnected from trunk, the more merging fun you will have to deal with.

Another thing I’d recommend is removing any branches as soon as you work the changes back into trunk. There’s really no reason for branches to just sit around.

As a tool though, the only time I’d really use a branch in SVN world, is when I’m touching lots of different parts of a system and I just need further testing before bringing my changes to trunk. For the casual change, I’d rather just not deal with that. A better idea is to setup a local repo of some sort and just work off that.


I was curious to see what git was all about. Being an avid Linux user, I can’t say that Linus has led me astray in the past… Also, to see if the branching really did make more sense in that world. I must say that it’s unbelievable. And as Linus said, git really does get you to interact differently with your repository. Because branching is done so well and you switch contexts so easily, I can see myself making branches A LOT more often. How it works is you create a branch and that branch kind of happens in the background. To actually view the branch you have to switch contexts, by calling the git checkout command. Once in that context there’s no drilling down to different branch directories. When you checkout the branch, you’re already in the branch and any changes stay in the branch. Then merging and deleting the branch are also very easy to do. It’s really quite impressive in a, yes that’s how it should be kind of way.

Right now, with subversion, I resist branching unless absolutely necessary. In SVN, it costs a lot (space) to branch, it’s very slow, it’s a pain to setup, and it’s tough to merge back.

And here is what it looks like in git (main tutorial)

Initializing a project (run these command within directory of project)
$ git init
$ git add .
$ git commit -m "Initial test"

Editing a file
$ vi modify_some_file
$ git add modify_some_file
$ git commit -m "Test"

Ok, now back to the topic of merging.
Create the branch and check it out. (‘git branch’ shows you which branch is the active branch)
$ git branch
$ git branch new_branch
$ git branch
$ git checkout new_branch
$ git branch

Edit a file
$ vi perl.txt
$ git commit -a -m "Expermintal test"

Change context to main branch (master)
$ git checkout master
$ less perl.txt

Merge new branch
$ git merge new_branch
$ less perl.txt

Delete the branch
$ git branch -d new_branch

Categories: git, Subversion Tags:

Python documentation

April 29th, 2009 2 comments

Was looking into auto-generated documentation for my python code and came across the following projects: pydoc, epydoc, and sphinx. Pydoc was pretty limited and didn’t output the most useful data. Epydoc is quite easy to use and does a great job at showing all your classes, functions, and variables. And then there was Sphinx. Sphinx is really the end-all and be-all documentation tool. It does a lot and lets you do a lot, BUT you have to put a little time into it. So if the documentation is just for your own purposes, it might not be worth it. If the documentation’s for an open source project, it’s probably worth the fuss, because it’s really not that bad and makes some really good looking docs. My one further point on this, is that the other tools are very limited in scope compared to Sphinx. You use Sphinx as a tool to write documentation outside the documentation in your code. The other tools pretty much strip the doc-strings from your code and make them pretty. Definitely worth looking into Sphinx for any serious open source project.

As an aside, I always wondered what Django used to make their documentation, and now it seems it was Sphinx all along.

epydoc --html python_file_1 python_file_2 python_file_3 version -o packrat_docs

By far the nicest of the three tools is Sphinx.
The Python documentation was done using Sphinx:
Sphinx was a little confusing to setup. First off there was a dependancy to jinja2 that really wasn’t spelled out (beyond the errors that came up during install).

So after installing ‘jinja2′ it was as simple as running
sudo easy_install -U Sphinx

Command looks something like this:
pydoc -w python_file-1
Seems to want the data to fit a certain setup.

Categories: Python Tags:

Ignore Python bytecode files in svn

April 27th, 2009 No comments

When loading up subversion’s status command it is quite annoying to get a list of files with the extension “pyc” in the list of files to look through. What you can do is setup rules within subversion to ignore these files. Subversion calls these settings “properties” and you can add them to different levels of your files (which actually can be confusing). What happened in my situation is that one of the folders I was working on did not have this value set, so that folder’s bytecode files were showing up but not any of the others.

The command is pretty simple:
svn propset svn:ignore "*.pyc" folder_name/

To view those properties that are set to a folder simply do:
svn proplist folder_name/

To delete the “svn:ignore” property do:
svn propdel svn:ignore folder_name/

Categories: Python, Subversion Tags: