From: Karl von Laudermann <doodpants@...>
Date: 2005-05-13T23:05:29+09:00
Subject: Re: Go through directories recursively

Robert Klemme wrote:
> Robert Klemme wrote:
> >
> > require 'find'
> >
> > def edit_directory(dir)
> >   Find::find(dir) do |f|
> >     if /\.jsp$/i =~ f and File.file? f
> >       # do something with f
> >     end
> >   end
> > end
> >
> > Kind regards
> >
> >     robert
>
> PS: You can also do
>
> Dir["**/*.jsp"].each do |f|
>   if File.file? f
>     # do something with f
>   end
> end

Question: what if the operation you want to perform is to delete
directories or files? From my understanding of Find#find, it yields
directories breadth-firsh rather than depth first. So if you want to
delete a directory yielded to your block, do you have to call
Find#prune on it to avoid messing up the traversal?

Likewise for Dir["**/*.jsp"]. Does this form first create an internal
array of file names before yielding them, or does it yield each file as
it inspects each directory? If the latter, does the traversal get
messed up if you delete a file out from under it?

I didn't know about either of the two above options, so the first time
I needed to traverse directories recursively (to delete files, no less)
I rolled my own solution, shown below. Until I know that either of the
above options is safe for this, I will continue to use it.

# Yields the name of each directory within the specified directory
# recursively. Order is depth-first, to accommodate deleting files in
the
# yielded directory from within the block. Passed in directory is
yielded last
def each_dir(base, &block)
    Dir.entries(base).each do |n|
        unless (n == '.') || (n == '..') # Don't traverse . or ..
            n = File.join(base, n) unless base == '.'
            if File.directory?(n)
                each_dir(n, &block)
                yield n
            end
        end
    end
    yield base
end