Seventh SoCal Piggies Meeting

The SoCal Piggies had their seventh meeting at USC (Salvatori Computer Science Center) on September 13th at 7:00 PM. Eight Piggies attended -- Daniel Arbuckle, Diane Trout, Grig Gheorghiu, Howard Golden, Manuel Garcia, Mark Kohler, Steve Williams and Titus Brown.

Diane Trout talked about her experiences with Trac, an integrated wiki/issue tracker/source code browser/interface to revision control systems. The chief virtue of Trac is that it's written in Python. The other chief virtue is that it looks good, which may be the reason why it's starting to get traction (pardon the pun) in different open souce projects -- and here we have to mention Django, which uses Trac in the Code section of its Web site. The Django repository site is a good example of how attractive and polished a Trac site can be.

Diane also said the setup of Trac was relatively easy.

Trac supports Subversion out of the box, but Darcs can also be integrated into it, as Diane showed us. The guy who integrated Darcs is the same guy who wrote Tailor, a Python package that knows how to migrate changesets among tons of revision control systems.

Another nice thing about Trac is that it allows you to easily link from a bug description into the source code referenced by that bug. For example, to link to the README file, simply include source:README in your bug description. The reverse is also true, i.e. you can reference bug numbers when in your code check-in comments -- for example, to reference bug number 23, simply include #23 or ticket:23 in your commit comments. Here is more information on specific Trac Wiki formatting rules.

Diane also mentioned TestOOB, which is a unit test tool that extends the default unittest module with things such as HTML/XML output and colored console output. The thing that Diane found most useful was that, when run with --debug, testoob drops you into the PDB debugger when it encounters any test failures.

Titus Brown was next, and he talked about why he likes Darcs. Darcs is a distributed revision control system with some solid math theory behind it. All working copies of Darcs are full repositories, and you can easily sync repositories by means of 'push' and 'pull' commands. Patches can be sent from one developer to another via email, and the repositories can very easily be made available in a read-only format by simply making them accessible through the Web, for example by putting them somewhere under the DocumentRoot directory of your Apache web server (in fact, this was one of the main reasons why Titus switched from CVS to Darcs).

One minor Darcs annoyance is the difficulty to install from source (installing from binary is obviously no problem, assuming a binary exists for your distribution). Darcs is written in Haskell, so the Glasgow Haskell Compiler is required, and if you wish to install Haskell from source, you have a boot-strapping problem, because Haskell is written in itself.

Had some commentary about how nice Darcs would be for people managing projects with users on more than one site, with subtle changes in the configuration at each site. Each site would have its own darcs repository, along with the main one. Patch the main repository or an individual site, and then cherry-pick the changes to distribute to all. Very clean.

Many thanks to Diane and Titus for presenting and to Daniel for hosting the meeting.

The next meeting will be at USC again. Here are some topics for our next meetings:

• PIL overview (Brian Leair)

• matplotlib tutorial (Diane Trout)

• metakit overview (Howard Golden)

• twill presentation (Titus Brown)

• Selenium tutorial (Grig Gheorghiu)