command.rb

class Command

  attr_reader :description

  def initialize(description)
    @description = description
  end

  def execute
  end
end

class CompositeCommand < Command
  def initialize
    @commands = []
  end

  def add_command(cmd)
    @commands << cmd
  end

  def execute
    @commands.each {|cmd| cmd.execute}
  end

  def description
    description = ''
    @commands.each {|cmd| description += cmd.description + "\n"}
    description
  end
end

class CreateFile < Command
  def initialize(path, contents)
    super("Create file: #{path}")
    @path = path
    @contents = contents
  end

  def execute
    f = File.open(@path, "w")
    f.write(@contents)
    f.close
  end
end

class DeleteFile < Command
  def initialize(path)
    super("Delete file: #{path}")
    @path = path
  end

  def execute
    File.delete(@path)
  end
end

cmd = CompositeCommand.new
cmd.add_command(CreateFile.new("test.txt","hoge"))
cmd.add_command(DeleteFile.new("test.txt"))
cmd.execute
puts cmd.description