A Weekend’s Work at the Open Source Coalface

I got my hands dirty trying to fix a bug in Megg last week. My main motivation, for what turned out to be a long weekend’s work, was a desire to use Mike Clark’s pragmatic automation template announced back in July last year.

  • It wouldn’t load from the URL.
  • It wouldn’t load when I downloaded the zip file and copied it into ./templates/pragouto-template.
  • It wouldn’t load from ./pragauto-template.
  • In fact, it would only work when I added it to the templates collection in the project directory and added it to megg.jar using the “ant dist” target.

Intrigued, I uploaded the latest HEAD version from the CVS repository at sourceforge. The problem became even more intriging when I ran “ant test” on my new sandbox copy and it failed!

I dug deeper and found that the test failed because megg was looking for the provided java templates directory at./templates/java but failing to load ./java/megg.xml (not ./templates/java/megg.xml!) when later attempting to parse the megg properties.

When attempting to load a directory in the local folder ./java, megg would fail wto find template files in ./templates/java.

Templates would be loaded fine from the templates collection distributed in the Jar file (or added by me), which is why I assume the problem has not been noticed before.

I have attempted a fix to local file handling whereby megg now tries ./java then ./templates/java then $HOME/.megg/java and finally $HOME/.megg/templates/java before resorting to the jar file. If fact, my added code can actually find files at any path prefix, although I haven’t yet added that feature to the CLI (e.g. as an option -t <em>templates_dir</em>).

I made my changes by creating a new class to represent the TemplatesDirectory which also allows the code for handling local file templates to be somewhat simpler. I also took the opportunity to use commons-io to make file copy a bit more transparent and the commons-io groups’ best practices advice on using java.io.File object rather than strings to manipulate file names.

I haven’t yet tested the option to download from a URL (which didn’t work when I tried it before my changes). It’s next on my to-do list. However, I have invited Megg’s developer (Jeremy Rayner) to have a look and possibly merge my changes into a test branch for review. Just need to find out how to generate a patch file from CVS manual!

It was nice to be busy!

Author: cpjobling

Senior lecturer, College of Engineering, Swansea University