title: Use system namespaces for class libraries: good or bad
body: <p>Is it a good idea to use "system namespaces" in my class libraries?  </p>
  
  <p>Sample:</p>
  
  <pre><code>namespace System.Web {
      public static class RequestExtensions {
          public static bool IsPost(this HttpRequest r) {
              return string.Compare(r.HttpMethod, "POST", StringComparison.OrdinalIgnoreCase) == 0;
          }
      }
  }
  </code></pre>
  
  <p><strong>The advantage:</strong> no need to include additional uses-clauses (especially for extension methods), so all becomes available straight after adding reference to the library.</p>
  
  <p>The best sample is <a href="http://code.google.com/p/nunitex/" rel="nofollow noreferrer">NUnitEx</a> project (which uses NUnit's namespace).  </p>
  
  <p><strong>Disadvantages:</strong> potential name conflicts.</p>