• atomicobject.github.com/publisher

• github.com/atomicobject/publisher

• rubygems.org/gems/publisher

• rubydoc.info/gems/publisher/frames

publisher is a module for extending a class with event subscription and firing capabilities. This is helpful for implementing objects that participate in the Observer design pattern.

• Nice syntax for declaring events that can be subscribed for

• Convenient event firing syntax

• Subscribe / unsubscribe functionality

• Several method name aliases give you the flexibility to make your code more readable (eg, fire, notify, emit)

require 'rubygems'
require 'publisher'

class CustomerListHolder
  extend Publisher
  can_fire :customer_added, :list_cleared

  def add_customer(cust)
    (@list ||= []) << cust
    fire :customer_added, cust
  end

  def clear_list
    @list.clear
    fire :list_cleared
  end
end

holder = CustomerListHolder.new
holder.when :customer_added do |cust|
  puts "Customer added! #{cust}"
end
holder.when :list_cleared do
  puts "All gone."
end

holder.add_customer("Croz")
holder.add_customer("Matt")
holder.clear_list

• gem install publisher

(The MIT License)

Copyright © 2011 Atomic Object

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ‘Software’), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ‘AS IS’, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.