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POWhat is the use case for C# allowing to use new on a virtual method?
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copied!<p>Being mainly a Java developer, I was a bit surprised by the result when I one day accidentally used <em>new</em> keyword instead of <em>override</em>.</p> <p>It appears that the <em>new</em> keyword removes the "virtualness" of the method at that level in the inheritance tree, so that calling a method on an instance of child class that is downcasted to the parent class, will not resolve to the method implementation in the child class.</p> <p>What are the practical use cases for this behavior? </p> <p>Clarification: I understand the use of new when parent is not virtual. I'm more curious why the compiler allows new and virtual to be combined.</p> <p>The following example illustrates the difference:</p> <pre><code>using System; public class FooBar { public virtual void AAA() { Console.WriteLine("FooBar:AAA"); } public virtual void CCC() { Console.WriteLine("FooBar:CCC"); } } public class Bar : FooBar { public new void AAA() { Console.WriteLine("Bar:AAA"); } public override void CCC() { Console.WriteLine("Bar:CCC"); } } public class TestClass { public static void Main() { FooBar a = new Bar(); Bar b = new Bar(); Console.WriteLine("Calling FooBar:AAA"); a.AAA(); Console.WriteLine("Calling FooBar:CCC"); a.CCC(); Console.WriteLine("Calling Bar:AAA"); b.AAA(); Console.WriteLine("Calling Bar:CCC"); b.CCC(); Console.ReadLine(); } } </code></pre> <p>This produces the following output:</p> <pre><code>Calling FooBar:AAA FooBar:AAA Calling FooBar:CCC Bar:CCC Calling Bar:AAA Bar:AAA Calling Bar:CCC Bar:CCC </code></pre>

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