Why is this an issue?

With the advent of .NET framework version 2, certain practices have become obsolete.

In particular, exceptions should now extend System.Exception instead of System.ApplicationException. Similarly, generic collections should be used instead of the older, non-generic, ones. Finally when creating an XML view, you should not extend System.Xml.XmlDocument.

This rule raises an issue when an externally visible type extends one of these types:

• System.ApplicationException
• System.Xml.XmlDocument
• System.Collections.CollectionBase
• System.Collections.DictionaryBase
• System.Collections.Queue
• System.Collections.ReadOnlyCollectionBase
• System.Collections.SortedList
• System.Collections.Stack

Noncompliant code example

using System;
using System.Collections;

namespace MyLibrary
{
  public class MyCollection : CollectionBase  // Noncompliant
  {
  }
}

Compliant solution

using System;
using System.Collections;

namespace MyLibrary
{
  public class MyCollection : Collection<T>
  {
  }
}