Command pattern

command-pattern.rb

class Command
  def initialize(description, proc1, proc2)
    @description = description
    @function =  proc1
    @inverse = proc2
  end

  def execute
    @function.call unless @function.nil?
  end

  def unexecute
    @inverse.call unless @inverse.nil?
  end
end
class CreateFile < Command
  def initialize
    proc1 = Proc.new do
      puts "File Created"
    end
    proc2 = Proc.new do
      puts "File Destroyed"
    end
    super("creating new file", proc1, proc2)
  end
end

class CheckMemory < Command ##ireversible
def initialize
  proc1 = Proc.new do
    puts "Checking Memory..."
  end
  proc2 = Proc.new do
    puts "Mem Check need not be reversed"
  end
  super("Checking memory avalability", proc1, proc2)
  end
end

class Installer
  def initialize
    @commands = []
  end

  def add_command command
    @commands << command
  end

  def install
    @commands.each {|c| c.execute}
  end

  def uninstall
    @commands.reverse.each do |command|
      command.unexecute
    end
  end
end

installer = Installer.new
installer.add_command(CheckMemory.new)
installer.add_command(CreateFile.new)
installer.installinstaller.uninstall