CommandPatternRubyButton.rb

# Command interface
module ICommand

  def execute
    raise NotImplementedError
  end
end

# Concrete commands
class SubmitCommand

  include ICommand

  def initialize(receiver)
    @receiver = receiver
  end

  def execute
    @receiver.submit
  end
end

class DeleteCommand

  include ICommand

  def initialize(receiver)
    @receiver = receiver
  end

  def execute
    @receiver.delete
  end
end

# Invoker
class Button

  def initialize(command)
    @command = command
  end

  def click
    @command.execute
  end

  def switch_command(command)
    @command = command
  end
end

# Receiver
class Form

  def submit
    puts "form submitted"
  end

  def delete
    puts "form deleted"
  end
end

# Client
class Application

  def start
    form = Form.new

    submit_command = SubmitCommand.new(form)
    button = Button.new(submit_command)
    button.click

    delete_command = DeleteCommand.new(form)
    button.switch_command(delete_command)
    button.click
  end

end

app = Application.new
app.start