using Thin web server configuration in development , how to have eq. Apache RedirectMatch permanent

[Erwin]

In production, using Apache I can use RedirectMatch permanent to force url wo subdomain to use www.

<VirtualHost *:80>

    ServerName example.com

    RedirectMatch permanent ^/(.*) http://www.example.com/$1

</VirtualHost>

How can I get the same behavior when using Thin in dev mode ?    

need to change all  example.com/..   urls into  www.example.com/..   if I don't want to touch the routes  ?

thanks for feedback

[Erwin]

[SOLVED] but using Rails3 routes, maybe there is a better way ?

  host = Rails.application.config.action_mailer.default_url_options[:host]

  constraints(:host => host ) do

    root :to => redirect("http://www.#{host}")

    match '/*path', :to => redirect {|params| "http://www.#{host}/#{params[:path]}"}

  end