CODEWITHSUNDEEP
rubyobserver-pattern
rplaurindo
rplaurindo

Reputation: 1404

Observer Pattern not working on Ruby

I implemented this example below for use of the Observer Pattern on Ruby. I tried follow this, but didn't work.

require "observer"

class AAnyClass
  extend Observable
  changed
  notify_observers self
end

module AnObserver

  extend self

  def update constant
    p "Constant #{constant} has been called."
  end

  def observe constant
    constant.add_observer(self)
  end

end

AnObserver.observe AAnyClass
# must return "Constant AAnyClass has been called."
AAnyClass
# must return "Constant AAnyClass has been called."
AAnyClass

UPDATE

I converted the module AnObserver into a class, like this:

class AnObserver

  def update constant
    $stdout.puts "Constant #{constant} has been called."
  end

end

And change the class AAnyClass adding the Observable methods into a constructor and passing AnObserver instance as parameter to method add_observer, like this:

class AAnyClass
  include Observable

  def initialize
    add_observer AnObserver.new
    changed
    notify_observers AAnyClass
  end

end

And, finally, I added a little code that modifies the eigenclass of AAnyClass with the same code of the AAnyClass’s constructor.

class << AAnyClass
  extend Observable

  add_observer AnObserver.new
  changed
  notify_observers AAnyClass
end
AAnyClass

AAnyClass.new
AAnyClass.new

That’s it.

Upvotes: 0

Views: 280

Answers (1)

akofink
akofink

Reputation: 689

I think you are using modules and "extends" where you should be using classes and "includes". Something like this might be what you're looking for:

require "observer"

class AAnyClass
  include Observable

  def run
    changed
    notify_observers(self)
  end
end

class AnObserver

  def initialize(ob)
    ob.add_observer(self)
  end

  def update constant
    p "Constant #{constant} has been called."
  end

  def observe constant
    constant.add_observer(constant)
  end

end

ob = AAnyClass.new
AnObserver.new ob
ob.run

Upvotes: 1

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