[MacRuby-devel] Bizarre behaviour with an instance variable

I find the following behaviour a little bizarre: At the macirb prompt (0.8) fileManager = NSFileManager.defaultManager @theProjectRoot = '/Users/martin/work/macruby/lots_of_files' => "/Users/martin/work/macruby/lots_of_files"

...

filenames = fileManager.contentsOfDirectoryAtPath(@theProjectRoot, error:nil).map {|f| theProjectRoot.stringByAppendingPathComponent(f) } NameError: undefined local variable or method `theProjectRoot' for main:TopLevel

If I create a local variable with the name theProjectRoot, then the statement runs correctly. According to the documentation, NSFileManager.defaultManager.contentsOfDirectoryAtPath requires a string; the scope of the variable should be irrelevant, shouldn't it?