state_machine

Namespaces

When a namespace is configured for a state machine, the name provided will be used in generating the instance methods for interacting with states/events in the machine. This is particularly useful when a class has multiple state machines and it would be difficult to differentiate between the various states / events.

For example,

  class Vehicle
    state_machine :heater_state, :initial => :off, :namespace => 'heater' do
      event :turn_on do
        transition all => :on
      end

      event :turn_off do
        transition all => :off
      end
    end

    state_machine :alarm_state, :initial => :active, :namespace => 'alarm' do
      event :turn_on do
        transition all => :active
      end

      event :turn_off do
        transition all => :off
      end
    end
  end

The above class defines two state machines: heater_state and alarm_state. For the heater_state machine, the following methods are generated since it's namespaced by heater:

• can_turn_on_heater?
• turn_on_heater
• ...
• can_turn_off_heater?
• turn_off_heater
• ..
• heater_off?
• heater_on?

As shown, each method is unique to the state machine so that the states and events don't conflict. The same goes for the alarm_state machine:

• can_turn_on_alarm?
• turn_on_alarm
• ...
• can_turn_off_alarm?
• turn_off_alarm
• ..
• alarm_active?
• alarm_off?