Dealing with nothing

The null object pattern has gained increased popularity in some parts of the Ruby community in recent years. With the null object pattern, when you deal with another object that may or may not be available, instead of using nil to represent the case where the other object is not available, you use a separate object that implements the same methods.

As an example of this, let's say you are writing an internal application for a company, and you need to represent employees using an Employee class. For each employee, you are tracking the name, position, phone, and supervisor of the employee:

class Employee
  attr_reader :name
  attr_reader :position
  attr_reader :phone
  def initialize(name, position, phone, supervisor)
    @name = name
    @position = position
    @phone = phone
    @supervisor = supervisor
  end

There is...