From: Paul van Delst <Paul.vanDelst@...>
Date: 2007-08-29T08:10:05+09:00
Subject: Deleting empty directories

Hello,

I'm putting together a script to automatically update a repository working copy. The 
scenario is such that the versioned working copy itself is not being modified, but I am 
simply rsync'ing changes from an unversioned source (i.e. just a bunch of directories), 
and then committing (and then tagging) those files. It sounds weird, I know, but it's just 
temporary. Honest.

Anyway, the need has arisen to delete empty directory heirarchies (rsync will delete the 
files but not the directories because of the .svn subdirs). What I've done so far is this:

   require 'fileutils'

   def empty_dirs
     @current.collect do |f|
       f if (File.directory?(f) && Dir.glob("#{f}/*").empty?)
     end.compact
   end

   def remove_empty_dirs
     while not empty_dirs.empty?
       empty_dirs.each {|d| FileUtils.rm_rf(d)}
     end
   end

where the @current contains the updated list of files in my versioned working copy after I 
rsync'd, but before I started comparing the changes in my working copy. I created a dummy 
repository with a relatively complicated heirarchy of directories to test the above and it 
seems to work. However, two things bug me:

Firstly, in empty_dirs, I think

   f if (File.directory?(f) && Dir.glob("#{f}/*").empty?)

looks ugly. My limited experience is that if something looks ugly it can usually be 
expressed better. I haven't used collect too much either, so its intricacies escape me.


Secondly, I prefer not to test for negatives, as in

   while not empty_dirs.empty?

I also would rather not have an open loop either, but if a directory contains empty 
subdirectories, the parent directory is not considered empty, and etc. etc. As you can 
probably tell, recursion is not my strong point.

Would any kind soul out there care to provide any pointers for cleaning up the methods above?

Thanks for any info,

cheers,

paulv

p.s. BTW, I think the remove_empty_dirs method still needs to remove the deleted 
directories from @current to prevent them being tested again in the next call to empty_dirs.