Eclipse Markers

I’m trying to develop a plugin for Eclipse that uses jslint to validate your JavaScript. This involves scanning all the JavaScript code, and using markers to say where the problem lies.

I’ve almost got this done. But there was the slight problem that when I clicked on the problem view, it took me to the beginning of the file (more or less) instead of the line I should have gone to.

After hours of searching, wading through the debugger, etc, I finally managed to figure out what was going on.

  • You can’t set IMarker.LINE_NUMBER and IMarker.CHAR_START together—they’re mutually exclusive.
  • IMarker.CHAR_START and IMarker.CHAR_END refer to offsets from the start of the file, not the start of the line.

Needless to say, this is not documented anywhere. Eclipse is feeling rather programmer-hostile right now.



A while ago, I wrote a small wrapper around jslint in Perl: JavaScript-JSLint. However, it’s a real pain to use. There’s a dependency on JavaScript, which in turn needs a compiled version of spidermonkey.

On a recent Java project at $WORK, I wanted to use jslint as part of our unit tests—evil JavaScript be gone! I hacked together a small junit test involving Rhino and a filewalker. It’s worked surprisingly well; our JS code has stayed quite readable.

However, I was bugged by the implementation. So, I’ve rewritten it into a slightly more sensible form. This is now available as jslint4java. The main interface is command line, which is nice as it’s completely self-contained now. But there is also an API which lets you call it from unit tests.

  % java -jar jslint+rhino.jar application.js
  jslint:application.js:11:9:Line breaking error ')'.
  jslint:application.js:11:10:Missing semicolon.

It’s also been the first time I’ve used enum classes in Java 5. They’re really cute. Being able to enumerate all possible values at run time is really handy. Plus, being able to define additional methods is really handy.

Future directions include:

  • More help towards integrating this into a junit test easily.
  • An Eclipse plugin would be nice, so that you can get the jslint warnings pop up in the Problems view.

Google Code Hosting – svn import

I’ve just started a new project on Google Code Hosting (of which more later). I’ve been developing it in a local svn repository, and I’d like to transfer it up to the google svn server.

This isn’t easy. Google help has How do I import an existing Subversion repository?, but that’s only half the answer. The problem is that I develop many projects in one single repository (I find it easier to manage). So I wanted to export a subset of my repository to google.

Sadly, svnsync doesn’t support that.

The workaround is simple (yet tiresome). You have to create a mini-repository containing just the subset of the original repository you want, then send that to google. This is what I came up with to export just /project.

  % svnadmin create /tmp/project-repos
  % svnadmin dump -q /home/svn/public |
  > svndumpfilter include /project --renumber-revs -drop-empty-revs |
  > svnadmin load -q /tmp/project-repos

Of course, now that I have the subset isolated, the path structure is wrong. Everything is living under /project/trunk instead of /trunk. So, we have to fix that.

  % svn mv file:///tmp/project-repos/project/trunk file:///tmp/project-repos/
  % svn rm file:///tmp/project-repos/project -m 'No longer needed.'

Finally, I can use svnsync to send the changes to google:

  % svnsync init --username file:///tmp/project-repos
  % svnsync sync --username file:///tmp/project-repos

Phew. What a palaver. It would have been nice if they could accept a file containing the output of svnadmin dump instead…