title: Opencart's $this->config->get('module_var_name')
body: <p>I'm trying to customize an Opencart payment module, I see many places where config info is being used, but I cant find anything that creates what variables are in use. I know in the admin pages if I select 'paypal standard' I can set all the 'config' info, but I cant find the 'model' underlining it, is there a model, I wish to create a new config setting, settable inside the admin page</p>
  
  <p>How does the admin page know which variables to set? If I change the admin 'view' for the payment module to show a new setting, will that setting automatically be available in the catalog?</p>
  
  <p>example of some of the config data in use...</p>
  
  <p>admin\view\template\payment\pp_standard.tpl (paypal admin template), allows 'test mode' to be set....</p>
  
  <pre><code>&lt;tr&gt;
          &lt;td&gt;&lt;?php echo $entry_test; ?&gt;&lt;/td&gt;
          &lt;td&gt;&lt;?php if ($pp_standard_test) { ?&gt;
            &lt;input type="radio" name="pp_standard_test" value="1" checked="checked" /&gt;
            &lt;?php echo $text_yes; ?&gt;
            &lt;input type="radio" name="pp_standard_test" value="0" /&gt;
            &lt;?php echo $text_no; ?&gt;
            &lt;?php } else { ?&gt;
            &lt;input type="radio" name="pp_standard_test" value="1" /&gt;
            &lt;?php echo $text_yes; ?&gt;
            &lt;input type="radio" name="pp_standard_test" value="0" checked="checked" /&gt;
            &lt;?php echo $text_no; ?&gt;
            &lt;?php } ?&gt;&lt;/td&gt;
        &lt;/tr&gt;
  </code></pre>
  
  <p>catalog\controller\poayment\pp_standard.php (paypal catalog controller), uses above 'test mode' to determine which paypal Webservice URL to hit..</p>
  
  <pre><code>if (!$this-&gt;config-&gt;get('pp_standard_test')) {
      $curl = curl_init('https://www.paypal.com/cgi-bin/webscr');
  } else {
      $curl = curl_init('https://www.sandbox.paypal.com/cgi-bin/webscr');
  }
  </code></pre>
  
  <p>I was expecting to find a 'model' somewhere with 'pp_standard_test' defined somewhere, but I've found nothing, any help understanding this would be greatly appreciated.</p>
  
  <p>P.S. There is much advice online stating that the 'paypal standard' payment module is a good place to start, but more than likely, we wont be using paypal, it's the principle I'm trying to figure out.</p>