title: How do I use one config key in another?
body: <p>In Laravel 4's cascading configuration files I was able to reference one configuration key from another. For example, I liked to have <code>app.debug</code> set to true or false, and then I could switch error reporting to Sentry to the opposite of that in a different configuration file, by setting the relevant setting to <code>!Config::get('app.debug')</code>.</p>
  
  <p>I knew this was a little hairy because presumably whether the config value can be found depends on the order in which files are loaded. But I managed to get it working each time.</p>
  
  <p>I'm having no such luck in Laravel 5. I get a "class not found" error when I try to do <code>Config::get(...)</code> in a configuration file. Using the <code>config(...)</code> helper instead produces no error but the values aren't retrieved.</p>
  
  <p>The convention, of course, is to use environment variables, the <code>.env</code> file and <code>env(...)</code> to grab the values. That way each configuration key can use the value of the environment variable. That's fine and works, but I have some values which are shared between environments, and I do want some of these values to be committed to version control.</p>
  
  <p>Using the <code>.env.example</code> file isn't a good solution for me since I don't want to have to remember to copy values over to the <code>.env</code> file of each environment if they change.</p>
  
  <p>How can I store some configuration values in a way where they are shared between environments, are present in version control, and can be referenced in multiple configuration files?</p>