simple events and triggers in interpreter

lib/eventable.rb

@@ -0,0 +1,35 @@
+# A simple event registering/triggering module to mix into classes.
+# Events are stored in the `@events` ivar.
+module Eventable
+
+  # Register a handler for the given event name.
+  #
+  #   obj.on(:foo) { puts "foo was called" }
+  #
+  # @param [String, Symbol] name event name
+  # @return handler
+  def on(name, &handler)
+    event_table[name] << handler
+    handler
+  end
+
+  def off(name, handler)
+    event_table[name].delete handler
+  end
+
+  def event_table
+    return @event_table if @event_table
+    @event_table = Hash.new { |hash, key| hash[key] = [] }
+  end
+
+  # Trigger the given event name and passes all args to each handler
+  # for this event.
+  #
+  #   obj.trigger(:foo)
+  #   obj.trigger(:foo, 1, 2, 3)
+  #
+  # @param [String, Symbol] name event name to trigger
+  def trigger(name, *args)
+    event_table[name].each { |handler| handler.call(*args) }
+  end
+end

lib/interpreter.rb

@@ -1,10 +1,34 @@
 
+require "eventable"
+
 class Interpreter
+  include Eventable
 
   attr_accessor :instruction
+  attr_accessor :block
   attr_accessor :registers
 
   def initialize
     @registers = Hash[(0...12).collect{|i| ["r#{i}" , "undefined"]}]
   end
+
+  def start block
+    set_block  block
+  end
+  def set_block block
+    return if @block == block
+    @block = block
+    trigger(:block, block)
+    set_instruction block.codes.first
+  end
+  def set_instruction i
+    return if @instruction == i
+    @instruction = i
+    trigger(:instruction, i)
+  end
+  def tick
+    name = @instruction.class.name.split("::").last
+    send "execute_#{name}"
+  end
+
 end