lib/micromachine.rb in soveran-micromachine-0.0.5 vs lib/micromachine.rb in soveran-micromachine-0.0.6

@@ -1,30 +1,42 @@
 # Finite State Machine
 #
 # Usage:
 #
-#   fsm = MicroMachine.new(:new) # Initial state.
+#   machine = MicroMachine.new(:new) # Initial state.
 #
-#   fsm.transitions_for[:confirm] = { :new => :confirmed }
-#   fsm.transitions_for[:ignore] = { :new => :ignored }
-#   fsm.transitions_for[:reset] = { :confirmed => :new, :ignored => :new }
+#   machine.transitions_for[:confirm] = { :new => :confirmed }
+#   machine.transitions_for[:ignore]  = { :new => :ignored }
+#   machine.transitions_for[:reset]   = { :confirmed => :new, :ignored => :new }
 #
-#   fsm.trigger(:confirm)  #=> true
-#   fsm.trigger(:ignore)   #=> false
-#   fsm.trigger(:reset)    #=> true
-#   fsm.trigger(:ignore)   #=> true
+#   machine.trigger(:confirm)  #=> true
+#   machine.trigger(:ignore)   #=> false
+#   machine.trigger(:reset)    #=> true
+#   machine.trigger(:ignore)   #=> true
 #
+# It also handles callbacks that are executed when entering a different state.
+#
+#   machine.on(:confirmed) do
+#     puts "Confirmed"
+#   end
 class MicroMachine
   attr :transitions_for
   attr :state
 
   def initialize initial_state
     @state = initial_state
     @transitions_for = Hash.new
+    @callbacks = Hash.new { |hash, key| hash[key] = [] }
   end
 
+  def on key, &block
+    @callbacks[key] << block
+  end
+
   def trigger event
     if transitions_for[event][@state]
       @state = transitions_for[event][@state]
+      @callbacks[@state].each { |callback| callback.call }
+      true
     end
   end
 end