title: Check if property exists
body: <p>Is it possible to check if a property exists which are set using magic setter?</p>
  
  <pre><code>class Test
  {
      private $vars;
  
      public function __set($key, $value) {
          $this-&gt;vars[$key] = $value;
      }
  
      public function &amp;__get($key)
      {
          return $this-&gt;vars[$key];
      }
  }
  
  $test = new Test;
  
  $test-&gt;myvar = 'yay!';
  
  if (magic_isset($test-&gt;myvar)) {
  }
  </code></pre>
  
  <p>Or isn't it possible and I just need to setup another function in my class?</p>