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copied!<p>You would expose it as an <code>IEnumerable<T></code>, but not just returning it directly:</p> <pre><code>public IEnumerable<object> Objects { get { return obs.Select(o => o); } } </code></pre> <p>Since you indicated you only wanted <em>traversal</em> of the list, this is all you need.</p> <p>One might be tempted to return the <code>List<object></code> directly as an <code>IEnumerable<T></code>, but that would be incorrect, because one could easily inspect the <code>IEnumerable<T></code> at runtime, determine it is a <code>List<T></code> and cast it to such and mutate the contents.</p> <p>However, by using <code>return obs.Select(o => o);</code> you end up returning an iterator over the <code>List<object></code>, not a direct reference to the <code>List<object></code> itself.</p> <p>Some might think that this qualifies as a "degenerate expression" according to section 7.15.2.5 of the C# Language Specification. However, <a href="http://blogs.msdn.com/ericlippert/archive/2008/05/12/trivial-projections-are-usually-optimized-away.aspx" rel="nofollow noreferrer">Eric Lippert goes into detail as to why this projection isn't optimized away</a>.</p> <p>Also, people are suggesting that one use the <a href="http://msdn.microsoft.com/en-us/library/bb335435.aspx" rel="nofollow noreferrer">AsEnumerable extension method</a>. This is incorrect, as the reference identity of the original list is maintained. From the Remarks section of the documentation:</p> <blockquote>The <code>AsEnumerable<TSource>(IEnumerable<TSource>)</code> method has no effect other than to change the compile-time type of source from a type that implements <code>IEnumerable<T></code> to <code>IEnumerable<T></code> itself.</blockquote> <p>In other words, all it does is cast the source parameter to <code>IEnumerable<T></code>, which doesn't help protect referencial integrity, the original reference is returned and can be cast back to <code>List<T></code> and be used to mutate the list.</p>

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