A very basic but flexible approach to performing tasks on files and folders by invoking a callback object rather than acting directly on them

crawl.rb

# Doing a crawl, passing a Doer class and a couple of regexp to filter out the filenames


require 'crawler'

crawler = Crawler.new('/Users/mort/Documents', Doer, :patterns => [/foo/, /karma/])
crawler.crawl

crawler.rb

class Crawler
  
  # Goes through each file and folder inside the base folder and calls the 'do' method on a 'doer' callback object, passing the file/folder as a parameter
  # Options:
  # :skip_folders, :skip_files (boolean) for doing just that
  # :ignore_hidden (boolean) for ignoring hidden files
  # :patterns an array of regexps. Dir/files will only be passed to the doer object if its name match at least one of the regexps

  require 'doers'
  attr_reader :base

  def initialize(base, callback = nil, options = {})
    @base = base
    @callback = callback
    @options = options
  end

  def crawl_dir(dir)
    raise "Boom" unless File.directory?(dir)
    
    skip_folders = @options.delete(:skip_folders)
    skip_files = @options.delete(:skip_files)    
    ignore_hidden = @options.delete(:ignore_hidden) || true
    patterns = @options.delete(:patterns)

    Dir.foreach(dir) do |f|

      ok = true 

      next if ['.','..'].include?(f)
      next if f.match(/^\..*$/) if ignore_hidden

      if patterns.is_a?(Array) && !patterns.empty?
        ok = false
      
        patterns.each do |p|
          ok = true if !p.match(f).nil?
        end

        next unless ok
      end

      c = File.join(dir,f)

      if File.directory?(c) 
        @callback.send(:do, c) unless skip_folders
        crawl_dir(c) 
      else
	@callback.send(:do, c) unless skip_files  
      end	
    end
  end

  def crawl
    crawl_dir(@base)
  end

end

doer.rb

# An almost blank 'doer' class

class Doer
 
  def self.do(file)
    return unless File.exists?(file)

    if File.directory?(file)
      puts "Directory: #{file}"	
    else
      puts " -- #{file}"
    end
  end

end