Sha256: 6387c493406f7c2424b06e545f8c41e23d982f59779307200251632411436221
Contents?: true
Size: 1.44 KB
Versions: 7
Compression:
Stored size: 1.44 KB
Contents
# Copyright (C) 2003-2006 Kouichirou Eto, All rights reserved.
# This is free software with ABSOLUTELY NO WARRANTY.
# You can redistribute it and/or modify it under the terms of the GNU GPL 2.
require 'observer'
class Ticker ### Periodically fetch a stock price.
include Observable
def initialize(symbol)
@symbol = symbol
end
def run
lastPrice = nil
loop {
price = Price.fetch(@symbol)
print "Current price: #{price}\n"
if price != lastPrice
changed # notify observers
lastPrice = price
notify_observers(Time.now, price)
end
sleep 1
}
end
end
class Price ### A mock class to fetch a stock price (60 - 140).
def Price.fetch(symbol)
60 + rand(80)
end
end
class Warner ### An abstract observer of Ticker objects.
def initialize(ticker, limit)
@limit = limit
ticker.add_observer(self)
end
end
class WarnLow < Warner
def update(time, price) # callback for observer
if price < @limit
print "--- #{time.to_s}: Price below #@limit: #{price}\n"
end
end
end
class WarnHigh < Warner
def update(time, price) # callback for observer
if price > @limit
print "+++ #{time.to_s}: Price above #@limit: #{price}\n"
end
end
end
def check_observer_main
ticker = Ticker.new('MSFT')
WarnLow.new(ticker, 80)
WarnHigh.new(ticker, 120)
ticker.run
end
if $0 == __FILE__
check_observer_main
end
Version data entries
7 entries across 7 versions & 2 rubygems