[lnkForumImage]
TotalShareware - Download Free Software
Confronta i prezzi di migliaia di prodotti.
Asp Forum
 Home | Login | Register | Search 


 

Forums >

comp.lang.ruby

Deleting empty directories

Paul Van Delst

8/28/2007 11:06:00 PM

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.
2 Answers

dblack

8/28/2007 11:57:00 PM

0

Paul Van Delst

8/29/2007 1:47:00 PM

0

dblack@wobblini.net wrote:
> Hi --
>
> On Wed, 29 Aug 2007, Paul van Delst wrote:
>
[snip]
>> 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

[snip..asking for a better way]

> You're currently using collect plus compact, but you can actually just
> use select. (That's not a general equivalence, but in this case it
> applies.)
>
> @current.select do |f|
> File.directory?(f) && Dir["#{f}/*"].empty?
> end
>
> I'd be inclined to break things out a little. (Untested code follows
> -- please test on expendable data :-)
>
> require 'fileutils'
>
> def dirs
> @current.select {|f| File.dir?(f) }
> end
>
> def empty_dirs
> dirs.select {|d| Dir["#{d}/*"].empty? }
> end
>
> def non_empty_dirs
> dirs - empty_dirs
> end
>
> def remove_empty_dirs
> non_empty_dirs.each {|d| FileUtils.rm_rf(d) }
> end

Hello,

Excellent! David, thanks very much. The extra reduction of tasks is exactly what I was
looking for (it certainly is a skill that I am having difficulty mastering).

I changed the remove_empty_dirs to a) remove the empty, not non-empty, dirs (! :o), and b)
modify the @current file list:

def remove_empty_dirs
until empty_dirs.empty?
empty_dirs.each do |d|
@current.delete(d)
FileUtils.rm_rf(d)
end
end
end

Again, thanks very much.

cheers,

paulv