Method: Concurrent::IVar#add_observer

Defined in:
lib/concurrent/ivar.rb

#add_observer(observer = nil, func = :update, &block) ⇒ Object

Add an observer on this object that will receive notification on update.

Upon completion the ‘IVar` will notify all observers in a thread-safe way. The `func` method of the observer will be called with three arguments: the `Time` at which the `Future` completed the asynchronous operation, the final `value` (or `nil` on rejection), and the final `reason` (or `nil` on fulfillment).

Parameters:

  • observer (Object) (defaults to: nil) —

    the object that will be notified of changes

  • func (Symbol) (defaults to: :update) —

    symbol naming the method to call when this ‘Observable` has changes`

Raises:

  • (ArgumentError) 


80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
 
# File 'lib/concurrent/ivar.rb', line 80

def add_observer(observer = nil, func = :update, &block)
  raise ArgumentError.new('cannot provide both an observer and a block') if observer && block
  direct_notification = false

  if block
    observer = block
    func = :call
  end

  synchronize do
    if event.set?
      direct_notification = true
    else
      observers.add_observer(observer, func)
    end
  end

  observer.send(func, Time.now, self.value, reason) if direct_notification
  observer
end