Fixing up state machine docs

activemodel/README

@@ -154,3 +154,16 @@ functionality from the following modules:
   
   {Learn more}[link:classes/ActiveModel/Serialization.html]
     
+
+* Turning your object into a finite State Machine
+
+    ActiveModel::StateMachine provides a clean way to include all the methods
+    you need to transform your object into a finite State Machine...
+
+    light = TrafficLight.new
+    light.current_state       #=> :red
+    light.change_color!       #=> true
+    light.current_state       #=> :green
+
+  {Learn more}[link:classes/ActiveModel/StateMachine.html]
+

activemodel/lib/active_model/state_machine.rb

@@ -1,112 +1,152 @@
 module ActiveModel
-  # ==== Examples
-  #
-  #    class TrafficLight
+  
+  # ActiveModel::StateMachine provides methods that turn your object into a
+  # finite state machine, able to move from one state to another.
+  # 
+  # A minimal implementation could be:
+  # 
+  #    class EmailMessage
   #      include ActiveModel::StateMachine
-  #
+  #    
   #      state_machine do
-  #        state :red
-  #        state :green
-  #        state :yellow
-  #        state :blink
-  #
-  #        event :change_color do
-  #          transitions :to => :red, :from => [:yellow],
-  #            :on_transition => :catch_runners
-  #          transitions :to => :green, :from => [:red]
-  #          transitions :to => :yellow, :from => [:green]
-  #        end
-  #
-  #        event :defect do
-  #          transitions :to => :blink, :from => [:yellow, :red, :green]
-  #        end
-  #
-  #        event :repair do
-  #          transitions :to => :red, :from => [:blink]
-  #        end
+  #        state :unread
+  #        state :read
   #      end
-  #
-  #      def catch_runners
-  #        puts "That'll be $250."
+  #    
+  #      event :open_email do
+  #        transitions :to => :read, :from => :unread
   #      end
   #    end
+  # 
+  # === Examples
   #
-  #    light = TrafficLight.new
-  #    light.current_state        # => :red
-  #    light.change_color         # => true
-  #    light.current_state        # => :green
-  #    light.green?               # => true
-  #    light.change_color!        # => true
-  #    light.current_state        # => :yellow
-  #    light.red?                 # => false
-  #    light.change_color         # => true
-  #    "That'll be $250."
+  #   class TrafficLight
+  #     include ActiveModel::StateMachine
+  #   
+  #     attr_reader :runners_caught
+  #   
+  #     def initialize
+  #        @runners_caught = 0
+  #      end
+  #   
+  #     state_machine do
+  #       state :red
+  #       state :green
+  #       state :yellow
+  #       state :blink
+  #   
+  #       event :change_color do
+  #         transitions :to => :red, :from => [:yellow],
+  #           :on_transition => :catch_runners
+  #         transitions :to => :green, :from => [:red]
+  #         transitions :to => :yellow, :from => [:green]
+  #       end
+  #   
+  #       event :defect do
+  #         transitions :to => :blink, :from => [:yellow, :red, :green]
+  #       end
+  #   
+  #       event :repair do
+  #         transitions :to => :red, :from => [:blink]
+  #       end
+  #     end
+  #   
+  #     def catch_runners
+  #       @runners_caught += 1
+  #     end
+  #   end
+  #   
+  #   light = TrafficLight.new
+  #   light.current_state        # => :red
+  #   light.change_color!        # => true
+  #   light.current_state        # => :green
+  #   light.green?               # => true
+  #   light.change_color!        # => true
+  #   light.current_state        # => :yellow
+  #   light.red?                 # => false
+  #   light.change_color!        # => true
+  #   light.runners_caught       # => 1
+  # 
+  # * The initial state for TrafficLight is red which is the first state defined.
   #
+  #    TrafficLight.state_machine.initial_state      # => :red
   #
-  #  * The initial state for TrafficLight is red which is the first state defined.
+  # * Call an event to transition a state machine, e.g. <tt>change_color!</tt>.
+  #   You can call the event with or without the exclamation mark, however, the common Ruby
+  #   idiom is to name methods that directly change the state of the receivier with
+  #   an exclamation mark, so <tt>change_color!</tt> is preferred over <tt>change_color</tt>.
+  #    
+  #    light.current_state    #=> :green
+  #    light.change_color!    #=> true
+  #    light.current_state    #=> :yellow
+  # 
+  # * On a succesful transition to red (from yellow), the local +catch_runners+
+  #   method is executed
   #
-  #      # Want to know the initial_state?
-  #      TrafficLight.state_machine.initial_state      # => :red
+  #    light.current_state    #=> :red
+  #    light.change_color!    #=> true
+  #    light.runners_caught   #=> 1
   #
-  #  * On a succesful transition to red (from yellow), the local +catch_runners+
-  #    method is executed
+  # * The object acts differently depending on its current state, for instance,
+  #   the change_color! method has a different action depending on the current
+  #   color of the light
+  # 
+  #    light.change_color!    #=> true
+  #    light.current_state    #=> :red
+  #    light.change_color!    #=> true
+  #    light.current_state    #=> :green
   #
-  #  * The object acts differently depending on its current state, for instance,
-  #    the change_color! method has a different action depending on the current
-  #    color of the light
-  #
-  #  * Get the possible events for a state
-  #
-  #      TrafficLight.state_machine.events_for(:red)   # => [:change_color, :defect]
-  #      TrafficLight.state_machine.events_for(:blink) # => [:repair]
+  # * Get the possible events for a state
   #
+  #    TrafficLight.state_machine.events_for(:red)   # => [:change_color, :defect]
+  #    TrafficLight.state_machine.events_for(:blink) # => [:repair]
   #
   # The StateMachine also supports the following features :
   #
-  #  * Success callbacks on event transition
+  # * Success callbacks on event transition
   #
-  #      event :sample, :success => :we_win do
-  #        ...
+  #    event :sample, :success => :we_win do
+  #      ...
+  #    end
+  #
+  # * Enter and exit callbacks par state
+  #
+  #    state :open, :enter => [:alert_twitter, :send_emails], :exit => :alert_twitter
+  #
+  # * Guards on transition
+  #
+  #    event :close do
+  #      # You may only close the store if the safe is locked!!
+  #      transitions :to => :closed, :from => :open, :guard => :safe_locked?
+  #    end
+  #
+  # * Setting the initial state
+  #
+  #    state_machine :initial => :yellow do
+  #      ...
+  #    end
+  #
+  # * Named the state machine, to have more than one
+  #
+  #    class Stated
+  #      include ActiveModel::StateMachine
+  #    
+  #      strate_machine :name => :ontest do
   #      end
-  #
-  #  * Enter and exit callbacks par state
-  #
-  #      state :open, :enter => [:alert_twitter, :send_emails], :exit => :alert_twitter
-  #
-  #  * Guards on transition
-  #
-  #      event :close do
-  #        # You may only close the store if the safe is locked!!
-  #        transitions :to => :closed, :from => :open, :guard => :safe_locked?
+  #    
+  #      state_machine do
   #      end
+  #    end
+  #     
+  #    # Get the state of the <tt>:ontest</tt> state machine
+  #    stat.current_state(:ontest)
+  #    # Get the initial state
+  #    Stated.state_machine(:ontest).initial_state
   #
-  #  * Setting the initial state
+  # * Changing the state
   #
-  #      state_machine :initial => :yellow do
-  #        ...
-  #      end
-  #
-  #  * Named the state machine, to have more than one
-  #
-  #      class Stated
-  #        include ActiveModel::StateMachine
-  #
-  #        strate_machine :name => :ontest do
-  #        end
-  #
-  #        state_machine do
-  #        end
-  #      end
-  #
-  #      # Get the state of the <tt>:ontest</tt> state machine
-  #      stat.current_state(:ontest)
-  #      # Get the initial state
-  #      Stated.state_machine(:ontest).initial_state
-  #
-  #  * Changing the state
-  #
-  #      stat.current_state(:default, :astate)    # => :astate
-  #      # But you must give the name of the state machine, here <tt>:default</tt>
+  #    stat.current_state(:default, :astate)    # => :astate
+  #    # But you must give the name of the state machine, here <tt>:default</tt>
   #
   module StateMachine
     autoload :Event, 'active_model/state_machine/event'