title: C# how to extend and pass a parameter to an attribute
body: <p>I'm adding attributes to dynamically created parameters. One attribute implements interface IItemsSource and is used like this:</p>
  
  <pre><code>using Xceed.Wpf.Toolkit.PropertyGrid.Attributes;
  
  public class MySourceObject
  {
      [ItemsSource(typeof(MyCustomItemsSource))]
      public string SelectedString { get; set; }
  }
  
  public class MyCustomItemsSource : IItemsSource
  {
      public MyCustomItemsSource()
      {
      }
  
      public ItemCollection GetValues()
      {
          ItemCollection strings = new ItemCollection();
          strings.Add("A");
          strings.Add("B");
          strings.Add("C");
  
          // Here I want to add some items from a collection, passed to the class somehow
  
          return strings;
      }
  }
  </code></pre>
  
  <p>How can I pass a list of custom object to MyCustomItemsSource constructor?</p>