Notifier.rb

notifier.rb

#!/usr/bin/env ruby

module Notifier
  attr_reader :listeners

  def on(event, *xs, &b)
    @listeners ||= Hash.new {|h,k| h[k] = []}
    @listeners[event].push *xs, b
  end

  def off(event, &b)
    listeners[event].delete_if &b
  end

  def notify(event, &b)
    listeners[event].each &(b ? b : :call)
  end
end

if __FILE__ == $0
  class C
    include Notifier

    def foo
      notify :foo
    end

    def bar(*args)
      notify(:bar) {|x| x.(*args) }
    end
  end

  c = C.new

  c.on(:foo) { puts 'This is foo' }
  px = -> { puts 'This is foo 2' }
  c.on :foo, &px

  c.on(:bar) {|x| puts "This is bar: #{x}" }


  c.foo
  c.bar 'hello'

  c.off(:foo) {|x| x == px }

  c.foo
end

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