Created
March 31, 2015 21:49
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Design Pattern Frolics!
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class MessageDispatcher | |
def initialize | |
@observers = [] | |
end | |
def register(observer) | |
@observers << observer | |
end | |
def dispatch(message) | |
@observers.each do |observer| | |
observer.notify(message) | |
end | |
end | |
end | |
class ObserverFactoryFactory | |
def build(&block) | |
Class.new do | |
define_method :notify do |message| | |
block.call(message) | |
end | |
end | |
end | |
end | |
class OutputBuffer | |
def initialize(stream) | |
@messages = [] | |
@stream = stream | |
end | |
def <<(message) | |
@messages << message | |
end | |
def flush | |
@messages.each do |message| | |
@stream.print(message) | |
end | |
@messages = [] | |
end | |
end | |
buffer = OutputBuffer.new(File.new("output", "w")) | |
fizz_observer_factory = ObserverFactoryFactory.new.build do |message| | |
if message % 3 == 0 | |
buffer << "fizz" | |
end | |
end | |
buzz_observer_factory = ObserverFactoryFactory.new.build do |message| | |
if message % 5 == 0 | |
buffer << "buzz" | |
end | |
end | |
number_observer_factory = ObserverFactoryFactory.new.build do |message| | |
if message % 3 != 0 && message % 5 != 0 | |
buffer << message | |
end | |
end | |
null_observer_factory = ObserverFactoryFactory.new.build do |message| | |
buffer << "\n" | |
end | |
dispatcher = MessageDispatcher.new | |
dispatcher.register(fizz_observer_factory.new) | |
dispatcher.register(buzz_observer_factory.new) | |
dispatcher.register(number_observer_factory.new) | |
dispatcher.register(null_observer_factory.new) | |
1.upto(100).each do |i| | |
dispatcher.dispatch(i) | |
end | |
buffer.flush |
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