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copied!<p>I doubt I'd ever do this, but to answer your question, here's one way to achieve it in C# involving a little generic type inference and some abuse of operator overloading. You could write code like this:</p> <pre><code>if (x == Any.Of(1, 2)) { Console.WriteLine("In the set."); } </code></pre> <p>Where the <code>Any</code> class is defined as:</p> <pre><code>public static class Any { public static Any2<T> Of<T>(T item1, T item2) { return new Any2<T>(item1, item2); } public struct Any2<T> { T item1; T item2; public Any2(T item1, T item2) { this.item1 = item1; this.item2 = item2; } public static bool operator ==(T item, Any2<T> set) { return item.Equals(set.item1) || item.Equals(set.item2); } // Defining the operator== requires these three methods to be defined as well: public static bool operator !=(T item, Any2<T> set) { return !(item == set); } public override bool Equals(object obj) { throw new NotImplementedException(); } public override int GetHashCode() { throw new NotImplementedException(); } } } </code></pre> <p>You could conceivably have a number of overloads of the <code>Any.Of</code> method to work with 3, 4, or even more arguments. Other operators could be provided as well, and a companion <code>All</code> class could do something very similar but with <code>&&</code> in place of <code>||</code>.</p> <p>Looking at the disassembly, a fair bit of boxing happens because of the need to call <code>Equals</code>, so this ends up being slower than the obvious <code>(x == 1) || (x == 2)</code> construct. However, if you change all the <code><T></code>'s to <code>int</code> and replace the <code>Equals</code> with <code>==</code>, you get something which appears to inline nicely to be about the same speed as <code>(x == 1) || (x == 2)</code>.</p>

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