kvo-rb

KVO - Key-Value Observing for Ruby

KVO provides a mechanism that allows objects to be notified of changes to attributes of other objects. If you have used Key-Value Observing in a Mac OS X or iOS app, KVO will feel very familiar.

Installation

Add this line to your application's Gemfile:

gem 'kvo'

And then execute:

$ bundle

Or install it yourself as:

$ gem install kvo

Example

class Product
	attr_accessible :name, :price
	
	def initialize(name)
		self.name = name
	end
end

class StockController
	attr_accessible :products
	
	def initialize
		@products = []
	end
	
	def add_product(product)
		product.addObserver(self, :price)
		@products << product
	end
	
	def observeValueForKeyPath(keyPath, object)
		puts "New price for #{object.name}: #{object.send(keyPath)}"
	end		
end

fruit = Product.new('Banana')
stockManager = StockController.new
stockManager.add_product(fruit)
fruit.price = "0.30"
	=> "New price for Banana: 0.30"

License

MIT license