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POHow Do Generic Methods Know About Inaccessible Types? (Or "How I Lost a Dollar")
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  1. POHow Do Generic Methods Know About Inaccessible Types? (Or "How I Lost a Dollar")
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    copied!<p>So, we had a little bet on our team whether something would work or not. I lost. Here is the code:</p> <pre><code>using System; using System.Collections.Generic; using System.Linq; using System.Windows; using MyNamespace; namespace PrivateGeneric { /// &lt;summary&gt; /// Interaction logic for MainWindow.xaml /// &lt;/summary&gt; public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private void WhoIsRight_Click(object sender, RoutedEventArgs e) { var store = new GenericDataStore(); try { var data = new MyPrivateClass(); store.StoreTheData(data); object theData = store.GetTheData&lt;MyPrivateClass&gt;(); if (theData == null || !(theData is MyPrivateClass)) { throw new Exception(); } MessageBox.Show("Seann was right."); } catch (Exception) { MessageBox.Show("WOOOOOOOOOT!!!!! PHIL WINS!!!!!! HAHAHAHA!!!!!! PWNED!!!!!!!"); } } private class MyPrivateClass { } } } namespace MyNamespace { public class GenericDataStore { readonly List&lt;object&gt; _store = new List&lt;object&gt;(); public void StoreTheData&lt;T&gt;(T data) { _store.Add(data); } public object GetTheData&lt;T&gt;() { //How does "t is T" work if T is a private type unknown to this class? return _store.FirstOrDefault(t =&gt; (t is T)); } } } </code></pre> <p>The question of why it works is highlighted in the code. Does "is" not need to cast to T to determine whether it is in fact a T? And does it not need the type to be accessible to do so? Obviously that's not the case, so what mechanism does the highlighted line use to make its determination?</p>
 

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