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instance method

Observable#add_observer

add_observer(observer, func=:update)

# File tmp/rubies/ruby-3.2.0/lib/observer.rb, line 153
def add_observer(observer, func=:update)
  @observer_peers = {} unless defined? @observer_peers
  unless observer.respond_to? func
    raise NoMethodError, "observer does not respond to `#{func}'"
  end
  @observer_peers[observer] = func
end

Add observer as an observer on this object. So that it will receive notifications.

observer

the object that will be notified of changes.

func

Symbol naming the method that will be called when this Observable has changes.

This method must return true for observer.respond_to? and will receive *arg when notify_observers is called, where *arg is the value passed to notify_observers by this Observable

See also #changed #changed? also in 3.3 · 3.1 · 3.0

next ›#changed