Question

Possible Duplicate:
Look up all descendants of a class in Ruby

So, let’s say that we have:

class LivingBeing
  class Animal
  end

  class Bacteria
  end

  class Virus
  end
end

class Fungi < LivingBeing
end

How do I check what subclasses LivingBeing has? I know that we have Klass.ancestors but what’s the method to see the opposite of ancestors?

Answer 1

There’s nothing built into the core Ruby language that will do what you want – you’ll need to write your own. Here’s an example method subclasses_of(class_name_here) (below) that will return a list of subclasses of a particular class for you:

class Mammal
end

class Human < Mammal
end

class Dog < Mammal
end

def subclasses_of input
  ObjectSpace.each_object(Class).select { |klass| klass < input }
end

subclasses_of(Mammal)
 #=> [Human, Dog]

Btw, there’s an answer to this question here:

http://dzone.com/snippets/objectsubclasses