Public, Private, Protected

class Earth
 attr_accessor :myAttribute
 
 def hello
  bananna
  cherry
 end
 
 def goodbye(the_other_object)
  the_other_object.apple
  the_other_object.bananna # yes, you can call the protected method bananna on another object of the class
  
  begin
   the_other_object.cherry
  rescue StandardError => theError
   #
   puts “you can’t call the private method of another object even if it is the same class! #{theError}”
  end
 end
 
 public  # declaration not needed, just shown for clarity
  def apple
   puts “Someone called apple for #{@myAttribute} … anyone can call me”
  end

 protected
  def bananna
   puts “Someone called bananna for #{@myAttribute} … only this class may call me”
  end

 private
  def cherry
   puts “Someone called cherry for #{@myAttribute} … only other methods of this instance may call me”
  end
end

>> a = Earth.new
=> #<Earth:0x105107650>
>> a.myAttribute = “object A”
=> “object A”
>> a.apple
Someone called apple for object A anyone can call me
=> nil
>> a.hello
Someone called bananna for object A only this class may call me
Someone called cherry for object A only other methods of this instance may call me
=> nil
>> b = Earth.new
=> #<Earth:0x1050f50e0>
>> b.myAttribute = “object B”
=> “object B”
>> b.apple
Someone called apple for object B anyone can call me
=> nil
>> b.goodbye(a)
Someone called apple for object A anyone can call me
Someone called bananna for object A only this class may call me
you can’t call the private method of another object even if it is the same class! private method `cherry’ called for #<Earth:0x105107650 @myAttribute=”object A”>
=> nil