Creating an array of superclasses for a particular class

I'm trying to create an array of all the superclasses for the given class. I tried to solve this problem by using a loop. Why is this not working?

class Object
  def superclasses
    array = []
    klass = self.superclass
    unless klass == nil
      array << klass
      klass = klass.superclass
    end
    array
  end
end

class Bar
end

class Foo < Bar
end

p Foo.superclasses  # should be [Bar, Object, BasicObject]

Solution

unless isn't a loop. What you're looking for is until:

class Object
  def superclasses
    array = []
    klass = self.superclass
    until klass == nil
      array << klass
      klass = klass.superclass
    end
    array
  end
end

class Bar
end

class Foo < Bar
end

p Foo.superclasses # Prints "[Bar, Object, BasicObject]"

Furthermore, you don't need a new method for this. There's already a method called Module#ancestors which does basically what you want:

class Bar
end

class Foo < Bar
end

p Foo.ancestors # Prints "[Foo, Bar, Object, Kernel, BasicObject]"

Note that the return value of ancestors includes Foo itself, and modules which have been included in the inheritance chain, like Kernel. If you don't want that, you can define superclasses like this:

class Module
  def superclasses
    ancestors[1..-1].select{|mod| mod.is_a? Class }
  end
end

class Bar
end

class Foo < Bar
end

p Foo.superclasses # Prints "[Bar, Object, BasicObject]"