How do I get class-object from string “A::B::C” in Ruby?

Question

The following example fails

class A
  class B
  end
end
p Object.const_get \'A\' # => A
p Object.const_get \'A::B\' # => NameError: wrong constant name A::         


        

Answer 1

You'll have to manually "parse" the colons yourself and call const_get on the parent module/class:

ruby-1.9.1-p378 > class A
ruby-1.9.1-p378 ?>  class B
ruby-1.9.1-p378 ?>    end
ruby-1.9.1-p378 ?>  end
 => nil 
ruby-1.9.1-p378 > A.const_get 'B'
 => A::B 

Someone has written a qualified_const_get that may be of interest.