Method for create url with subdomain

gistfile1.rb

def with_subdomain(subdomain)  
    subdomain = (subdomain || "").to_s  
    subdomain += "." unless subdomain.empty?
    domain=request.domain.gsub! /^(\w){2}\./, ""
    [subdomain, domain].join
  end  

  def url_for(options = nil)  
    if options.kind_of?(Hash) && options.has_key?(:subdomain)
      options[:host] = with_subdomain(options.delete(:subdomain))
      options[:port] = request.port_string.gsub(':','') unless request.port_string.empty?
    end  
    super  
  end