title: set configuration constants depending on environment in rails
body: <p>I would like to define a constant (like the admin-email-adress) depending on the environment. What is the easiest way to do this?</p>
  
  <p>I'd like something like that, in development.rb (or test or production.rb):</p>
  
  <pre><code>ADMIN_EMAIL = "foo@bar.com"
  </code></pre>
  
  <p>And be able to access it by calling something like</p>
  
  <pre><code>ADMIN_EMAIL
  </code></pre>
  
  <p>Is there an easy way or do I have to do something like creating a module and initialize it and stuff (and in case you're wondering if I have any idea about this, unfortunately: I don't)</p>
  
  <blockquote>
    <p>It works this way, but one has to
    restart the server, for the constants
    to take effect.</p>
  </blockquote>