Can you tell me the three levels of method access control for classes and modules? What do they imply about the method?

All methods, no matter the access control, can be accessed within the class. But what about outside callers?

• Public methods enforce no access control — they can be called in any scope.
• Protected methods are only accessible to other objects of the same class.
• Private methods are only accessible within the context of the current object.

class AccessLevel
  def something_interesting
    another = AccessLevel.new
    another.public_method
    another.protected_method
    another.private_method
  end

  def public_method
    puts "Public method. Nice to meet you."
  end

  protected

  def protected_method
    puts "Protected method. Sweet!"
  end

  private 

  def private_method
    puts "Incoming exception!"
  end
end

AccessLevel.new.something_interesting
 #=> Public method.  Nice to meet you.
 #=> Protected method.  Sweet!
 #=> NoMethodError: private method ‘private_method’ called for
 #=>  #<AccessLevel:0x898c8>