gistfile1.rb

# -*- mode: ruby; coding: utf-8 -*-

#
# naive imitation #1 of NSNotificationCenter of Cocoa Framework
#

class NotificationCenter
  
  def self.default
    @instance ||= NotificationCenter.new
  end
  
  def initialize
    @queue = Queue.new
    @observers = []
    start
  end
  
  def add_observer(observer, method, name, object = nil)
    @observers << { :name => name, :observer => observer, :method => method, :object => object }
  end
  
  def remove_observer(observer, name = nil, object = nil)
    @observers.reject! do |o|
      o[:observer] == observer && (name.nil? || o[:name] == name) && (object.nil? || o[:object] == object)
    end
  end
  
  def post(name, object = nil)
    @queue.push({:name => name, :object => object})
  end
  
  
  private
  
  def start
    thread = Thread.start do
      loop do
        notification = @queue.pop
        notify(notification)
      end
    end
  end
  
  def notify(notification)
    name = notification[:name]
    object = notification[:object]
    
    @observers.each do |observer|
      if observer[:name] == name && (object == nil || observer[:object] == object)
        observer[:observer].send observer[:method], object
      end
    end
  end
  
end