From: "Hal E. Fulton" <hal9000@...>
Date: 2002-09-23T05:59:46+09:00
Subject: Getting a directory tree

Hi, all...

I have a little method here that gets a list of 
all directories under a certain starting dir.

I considered using "find" but it didn't jump
out as being any faster/better than doing it
myself. (E.g., extra method call of "prune")

This first method works:

  #
  # Return an array of directory names starting at the specified root
  #
  
  SEP = File::Separator
  
  def getdirs(root)
    dirs=Dir.entries(root) - [".", ".."]
    dirs.collect! {|x| test(?d,x) ? root+SEP+x : nil }
    dirs.compact!
    list = [root] + dirs
    dirs.each {|x| list += getdirs(x) }
    list
  end

but it's slow on my platform/version.

I figure if I speed it up on Windows, it will
remain fast on other platforms. (Not necessarily,
of course.)

Here's one new version. It DOES NOT work, and I'm
not sure why yet.

  def getdirs1(root)
    dirs=Dir.entries(root) - [".", ".."]
    temp = []
    dirs.each {|x| if test(?d,x) then temp << (root+SEP+x) end }
    list = [root] + temp
    dirs.each {|x| list += getdirs(x) }
    list
  end

So my two questions are:
  1. What's wrong with getdirs1 that I'm not seeing?
  2. How would you write this in a reasonably
     efficient way?

Cheers,
Hal