Ruby supports a third form of encapsulation other than public and private called protected.
protected makes a method private, but within the scope of a class rather than within a single object.
For example, you were unable to directly call a private method outside the scope of that object and its methods.
However, you can call a protected method from the scope of the methods of any object that's a member of the same class:
class Person def initialize(age) @age = age # from w ww. jav a 2 s . com end def age @age end def age_difference_with(other_person) (self.age - other_person.age).abs end protected :age end fred = Person.new(34) chris = Person.new(25) puts chris.age_difference_with(fred) puts chris.age
Here, the code uses a protected method so that the age method cannot be used directly, except within any method belonging to an object of the Person class.