From: David Masover <ninja@...>
Date: 2008-08-18T02:38:15+09:00
Subject: Where did this constant come from?

What's the simplest way to find out where a constant was defined?

I did come up with a way (probably partly ripped off from ActiveSupport), but 
it feels convoluted and fragile:


class Module
  def parent_namespace
    parts = self.name.split('::')
    if parts.length > 1
      parts.tap(&:pop).join('::').constantize
    else
      nil
    end
  end
  
  def eldest_ancestor_with_const name
    if const_defined? name
      klass = self
      self.ancestors.each do |ancestor|
        break if klass == Object
        break unless ancestor.const_defined? name
        klass = ancestor
      end
      klass
    else
      nil
    end
  end
  
  def find_const_parent name
    if Object.const_defined? name
      Object
    else
      klass = self
      until klass.const_defined? name
        klass = klass.parent_namespace
        return nil if klass.nil?
      end
      
      klass.eldest_ancestor_with_const(name)
    end
  end
end