From: "David A. Black" <dblack@...>
Date: 2004-04-09T20:09:59+09:00
Subject: Re: need help with recursion

Hi --

On Fri, 9 Apr 2004, ibotty wrote:

> > You'll still have the subdirectory problem.  Let's say you've got:
> > 
> >    a
> >    a/b
> >    a/b/under_score.txt
> > 
> > It will run the method for b, and filename will be set to
> > under_score.txt.  But when it stats it, it will stat it with respect
> > to a, unless you do a chdir to b or expand the path.
> 
> you can of course simply set filename to the right value. just change this,
> and it should work.
> 
>         File.rename(filename, newname)
> +       filename = newname
> end

That won't change the behavior of the original code.  The problem I'm
describing is that you're trying to stat a file when you're in the
wrong directory.  It's not the same as the problem involving renaming
the file.  

Here's an example, leaving out the renaming to show the problem:

  def find_files_broken(dir)
    Dir.new(dir).reject {|f| /\A\.\.?\z/.match(f)} .each do |f|
      if File.stat(f).file?
	puts "File: #{f}"
      elsif File.stat(f).directory?
	puts "Directory: #{f}"
	find_files(f)
      end
    end
  end

  find_files_broken(Dir.pwd)

Here's a modified example that works:

  def find_files(dir)
    Dir.chdir(dir) do
      Dir["*"].each do |f|
        if File.stat(f).file?
          puts "File: #{f}"
        elsif File.stat(f).directory?
          puts "Directory: #{f}"
          find_files(f)
        end
      end
    end
  end

  find_files(Dir.pwd)

The difference is that I've used Dir.chdir to make sure I'm addressing
the right space at the right time.  (This also allows me to use Dir.[]
instead of Dir.new, which saves the trouble of checking for "." and
"..".)


David

-- 
David A. Black
dblack@wobblini.net