title: Throwing multiple exceptions in .Net/C#
body: <p>In an application I work on, any business logic error causes an exception to be thrown, and the calling code handles the exception.  This pattern is used throughout the application and works well.  </p>
  
  <p>I have a situation where I will be attempting to execute a number of business tasks from inside the business layer.  The requirement for this is that a failure of one task should not cause the process to terminate.  Other tasks should still be able to execute.  In other words, this is not an atomic operation.  The problem I have is that at the end of the operation, I wish to notify the calling code that an exception or exceptions did occur by throwing an exception.  Consider the following psuedo-code snippet:</p>
  
  <pre><code>function DoTasks(MyTask[] taskList)
  {
    foreach(MyTask task in taskList)
    {
      try
      {
         DoTask(task);
      }
      catch(Exception ex)
      {
          log.add(ex);
      }
    }
  
    //I want to throw something here if any exception occurred
  }
  </code></pre>
  
  <p>What do I throw?  I have encountered this pattern before in my career.  In the past I have kept a list of all exceptions, then thrown an exception that contains all the caught exceptions.  This doesn't seem like the most elegant approach.  Its important to preserve as many details as possible from each exception to present to the calling code.</p>
  
  <p>Thoughts?</p>
  
  <hr/>
  
  <p>Edit: The solution must be written in .Net 3.5.  I cannot use any beta libraries, or the AggregateException in .Net 4.0 as mentioned by <a href="/users/23633/bradley-grainger">Bradley Grainger</a> (below) would be a nice solution for collection exceptions to throw.</p>