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    <p>The important thing to remember is that you must set the <code>SafeWaitHandle</code> property.</p> <p>From MSDN:</p> <blockquote> <p>When you derive from WaitHandle, use the SafeWaitHandle property to store your native handle operating system handle. You do not need to override the protected Dispose method unless you use additional unmanaged resources.</p> </blockquote> <p>Here is how I would do this.</p> <pre><code>public class QueueWaitHandle&lt;T&gt; : WaitHandle { private Queue&lt;T&gt; queue = new Queue&lt;T&gt;(); private ManualResetEvent signal = new ManualResetEvent(false); public QueueWaitHandle() { base.SafeWaitHandle = signal.SafeWaitHandle; } public void Enqueue(T item) { lock (queue) { queue.Enqueue(item); signal.Set(); } } public T Dequeue() { lock (queue) { T item = queue.Dequeue(); if (queue.Count == 0) { signal.Reset(); } return item; } } } </code></pre> <p>When done this way <code>Enqueue</code> acts like the <code>Set</code> method and <code>Dequeue</code> acts like the <code>Reset</code> method. So basically this works like a counting event where non-zero is signaled and zero is unsignaled. The queue is doing the counting in this case and it just happens to also hold data.</p> <p>I know you were asking about subclassing <code>WaitHandle</code> in general, but this specific data structure is more than just an exercise. It can be useful in some scenarios. I would not, however, call it a waitable queue because that implies, at least to me anyway, that the <code>Dequeue</code> operation will block when the queue is empty. Clearly that is not what will happen in this particular implemenation.</p>
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    1. POHow can I subclass WaitHandle?
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    1. USBrian Gideon
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    1. COYou can always have Dequeue(bool Blocking) but in any case that's the solution I was looking for. I would have expected to have protected Set and Reset or alternatively the protected ctor to have a parameter, as in WaitHandle(SafeWaitHandle Handle). I could find neither of those and that's what threw me off (shamefully I also missed the MSDN bit you quoted). My question was indeed general but it did arise from a real-life scenario and your solution will be put to good use. Thanks!
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