How to get the Parent of an Object's Class in Ruby
Greetings, friends! We learned in the last article how to get the class name of an object in Ruby. Now, it's time to get the parent class name! We can use the Class#superclass method to get the name of any object's parent class.
class Animal
def speak
puts "Grrr"
end
end
class Cat < Animal
def speak
puts "Meow!"
end
end
cat = Cat.new
puts cat.class # Cat
puts cat.class.superclass # Animal
puts cat.class.superclass.superclass # Object
Notice how we can figure out the inheritance chain by calling the superclass method multiple times. Eventually, we find out that our custom class inherits from Object which makes sense, since practically everything in Ruby is an object.
Lets look at integers, strings, booleans, and other types of objects. By calling the Class#superclass method, we can see that each of these types inherit from Object.
puts 0.class # Integer
puts 0.class.superclass # Numeric
puts 0.class.superclass.superclass # Object
puts "-------------"
puts 3.14.class # Float
puts 3.14.class.superclass # Numeric
puts 3.14.class.superclass.superclass # Object
puts "-------------"
puts "".class # String
puts "".class.superclass # Object
puts "-------------"
puts false.class # FalseClass
puts false.class.superclass # Object
puts "-------------"
puts true.class # TrueClass
puts true.class.superclass # Object
puts "-------------"
puts nil.class # NilClass
puts nil.class.superclass # Object
puts "-------------"
puts [].class # Array
puts [].class.superclass # Object
puts "-------------"
hash = {foo: 0, bar: 1, baz: 2}
puts hash.class # Hash
puts hash.class.superclass # Object
Getting the parent class name of an object is useful for learning the internals of Ruby or a Ruby library. You can also use the Class#superclass method to help you debug Ruby code. Sometimes, you may need to figure out how a variable's class hierarchy is defined. Calling the Class#superclass method multiple times is perfect for that.