debugging_procs.rb

require 'rubygems'
require 'ruby-debug'

def example
  debugger
  puts "Hello, I'm example"
end

def add_listener(&block)
  $listeners ||= Array.new
  $listeners.push(&block)
end

def ping_listeners
  $listeners.map(&:call)
end

# Drops into the debugger as expected
example

# Erm... WAT!?
add_listener(&method(:example))
ping_listeners