I come from a C# background, and have just started programming in Ruby. The thing is, that I need to know how I can raise events in my classes so that various observers can be triggered when things need to happen.
The problem is the books I have on Ruby don't even mention events, let alone provide examples. Is anyone able to help me?
The question has already been answered, but there's an observer built right into the standard library if you want to give that a look. I've used it in the past for a small game project, and it works very well.
Extremely simple Ruby listener. This is not exactly a replacement for .NET events, but this one is an extremely simple example of a very simple listener.
module Listenable
def listeners() @listeners ||= [] end
def add_listener(listener)
listeners << listener
end
def remove_listener(listener)
listeners.delete listener
end
def notify_listeners(event_name, *args)
listeners.each do |listener|
if listener.respond_to? event_name
listener.__send__ event_name, *args
end
end
end
end
To use:
class CowListenable
include Listenable
def speak
notify_listeners :spoken, 'moooo!'
end
end
class CowListener
def initialize(cow_listenable)
cow_listenable.add_listener self
end
def spoken(message)
puts "The cow said '#{message}'"
end
end
cow_listenable = CowListenable.new
CowListener.new(cow_listenable)
cow_listenable.speak
Output:
The cow said 'moooo!'