Dependency 1.0.0

Ruby
1

A Smalltalk-inspired dependency mechanism for Ruby. Like this:

class StockWatcher
  include Dependency::Methods
  def initialize(stock)
    stock.express_interest_in :price, :for => self, :send_back =>

:price_changed
end
def price_changed(old_price, stock)
# gets called whenever the stock object changes it’s price
end
end

Completely unrelated to Rails’ dependency code - similar to observers
though.

http://rubyforge.org/projects/dependency

gem install dependency

2

Joel VanderWerf wrote:

Tim F. wrote:

A Smalltalk-inspired dependency mechanism for Ruby.

You can do this with http://raa.ruby-lang.org/project/observable:

And observer.rb :slight_smile:

http://ruby-doc.org/stdlib/libdoc/observer/rdoc/index.html

3

Tim F. wrote:

  end
end

Completely unrelated to Rails’ dependency code - similar to observers
though.

http://rubyforge.org/projects/dependency

gem install dependency

You can do this with http://raa.ruby-lang.org/project/observable:

require ‘observable’

include Observable
include Observable::Match

class Stock
extend Observable

observable :price

def initialize price
@price = price
end

def sell
puts “selling at #{price}”
end
end

class StockWatcher
GREATER_THAN = proc do |price|
MatchProc.new { |test_price| test_price > price }
end

def initialize(stock)
stock.when_price CHANGES do |price, old_price|
puts “price = #{price} (was #{old_price.inspect})”
end

 stock.when_price GREATER_THAN[20] do
   stock.sell
 end

end
end

acme = Stock.new(10)
watcher = StockWatcher.new(acme)

10.step(30, 5) do |acme.price|
puts “—”
end

END

Output:

price = 10 (was nil)

price = 15 (was 10)

price = 20 (was 15)

selling at 25
price = 25 (was 20)

selling at 30
price = 30 (was 25)