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POFinalize/Dispose pattern in C#
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copied!<p>C# 2008</p> <p>I have been working on this for a while now, and I am still confused about some issues. My questions are below</p> <ol> <li><p>I know that you only need a finalizer if you are disposing of unmanaged resources. However, if you are using managed resources that make calls to unmanaged resources, would you still need to implement a finalizer?</p></li> <li><p>However, if you develop a class that doesn't use any unmanaged resources, directly or indirectly, can you implement the <code>IDisposable</code> so that clients of your class can use the 'using statement'? </p> <p>Would it be acceptable to implement the IDisposable just so that clients of your class can use the using statement?</p> <pre><code>using(myClass objClass = new myClass()) { // Do stuff here } </code></pre></li> <li><p>I have developed this simple code below to demonstrate the Finalize/dispose pattern:</p> <pre><code>public class NoGateway : IDisposable { private WebClient wc = null; public NoGateway() { wc = new WebClient(); wc.DownloadStringCompleted += wc_DownloadStringCompleted; } // Start the Async call to find if NoGateway is true or false public void NoGatewayStatus() { // Start the Async's download // Do other work here wc.DownloadStringAsync(new Uri(www.xxxx.xxx)); } private void wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e) { // Do work here } // Dispose of the NoGateway object public void Dispose() { wc.DownloadStringCompleted -= wc_DownloadStringCompleted; wc.Dispose(); GC.SuppressFinalize(this); } } </code></pre></li> </ol> <p>Question about the source code:</p> <ol> <li><p>Here I have not added the finalizer, and normally the finalizer will be called by the GC, and the finalizer will call the Dispose. As I don't have the finalizer, when do I call the Dispose method? Is it the client of the class that has to call it?</p> <p>So my class in the example is called NoGateway and the client could use and dispose of the class like this: </p> <pre><code>using(NoGateway objNoGateway = new NoGateway()) { // Do stuff here } </code></pre> <p>Would the Dispose method be automatically called when execution reaches the end of the using block, or does the client have to manually call the dispose method? i.e.</p> <pre><code>NoGateway objNoGateway = new NoGateway(); // Do stuff with object objNoGateway.Dispose(); // finished with it </code></pre></li> <li><p>I am using the webclient class in my <code>NoGateway</code> class. Because the webclient implements the IDisposable interface, does this mean that the webclient indirectly uses unmanaged resources? Is there a hard and fast rule to follow about this? How do I know that a class uses unmanaged resources?</p></li> </ol>

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