title: Symfony2: Multi-level parameters in YML
body: <p>Here is what I want to do. I've got some yml file like...</p>
  
  <p>My custom yml file :</p>
  
  <pre><code># app/config/sv_parameters.yml
  parameters:
    sv_email:
      debug: "debug@debug.com"
      admin: "admin@admin.com"
      ...
  </code></pre>
  
  <p>The config.yml file, importing my custom params :</p>
  
  <pre><code># app/config/config.yml
  imports:
    - { resource: sv_parameters.yml }
  ...
  </code></pre>
  
  <p>The config_dev.yml, importing the config.yml, and using a sub-parameter of my custom yml file :</p>
  
  <pre><code># app/config/config_dev.yml
  imports:
  - { resource: config.yml }
  
  swiftmailer:
    delivery_address: "%sv_email.debug%"
  </code></pre>
  
  <p>But, when I <code>clear:cache</code> :</p>
  
  <pre><code>You have requested a non-existent parameter "sv_email.debug".
  </code></pre>
  
  <p>I know in PHP multi-level parameters are arrays. But does that mean we can access them in pure YML ?</p>
  
  <p>I could write my <code>sv_email</code> parameters inline, but that's not as clean as multi levels..</p>