uri.rb

# Objects of this class are *almost* a URI!

class AlmostURI < String; end

[AlmostURI, String, Symbol].each do |klass|
  klass.class_eval do
    def / urlpart
      AlmostURI.new [self, urlpart].join('/')
    end

    def method_missing meth, *args
      AlmostURI.new [self, urlpart].join('.')
    end
  end
end

def method_missing meth, *args
  if args.size == 1 and args.first == :/
    return AlmostURI.new [self, ':/'].join('.')
  else
    super
  end
end

p((http://:google.com/:test.rb).to_s)