title: Is it possible to extend an attribute?
body: <p>In an app, I use different frameworks/technologies to serialize/deserialize objects. To ignore properties in the objects there are attributes like <code>BsonIgnore</code>  or <code>JsonIgnore</code>.</p>
  
  <pre><code>[JsonIgnore]
  [BsonIgnore]
  public bool MyProperty
  {
      get;
      set; 
  }
  </code></pre>
  
  <p>How can I create an attribute that extends from <code>BsonIgnore</code> and <code>JsonIgnore</code> so that I only need to specify one attribute for <code>MyProperty</code>? </p>
  
  <p>The following does not work as an attribute has to extend <code>System.Attribute</code>.</p>
  
  <pre><code>[AttributeUsage(AttributeTargets.Class)]
  public class MyIgnoreAttribute : BsonIgnore, JsonIgnore
  { ... }
  
  -------------------------
  
  [MyIgnore]
  public bool MyProperty
  {
      get;
      set; 
  }
  </code></pre>