Polymorphism can work with objects of multiple types and classes.
For example, the + method works for adding numbers, joining strings, and adding arrays together.
What + does depends entirely on what type of things you're adding together.
Here's a Ruby interpretation of a common demonstration of polymorphism:
class Animal attr_accessor :name # w w w. j a v a 2s . co m def initialize(name) @name = name end end class Cat < Animal def talk "Meaow!" end end class Dog < Animal def talk "Woof!" end end animals = [Cat.new("Flossie"), Dog.new("Clive"), Cat.new("Max")] animals.each do |animal| puts animal.talk end
Here, you define three classes: an Animal class, and Dog and Cat classes that inherit from Animal.
In the code, you create an array of various animal objects: two Cat objects and a Dog object.
Next, you iterate over each of the animals, and on each loop you place the animal object into the local variable, animal.
Last, you run puts animal.talk for each animal in turn.
As the talk method is defined on both the Cat and Dog class, but with different output, you get the correct output of two "Meaow!"s and two "Woof!"s.