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    copied!<blockquote> <p>"I've tried instantiating a Collection directly instead of a List and that doesn't seem to work."</p> </blockquote> <p>What error do you get? You can definitely create an instance of <code>Collection&lt;T&gt;</code> directly, it is not an abstract class and it has several public constructors, including one that's parameter-less. You can do this, for example:</p> <pre><code>var values = new System.Collections.ObjectModel.Collection&lt;int&gt; { 1,2,3,4 }; </code></pre> <p>I noticed your sample code has a <code>GenericTickType</code> and a <code>TickType</code>. Is this a mistake or do you actually have two classes? You said it's an enum (which one?), so one cannot possibly derive from the other. If they are two enum types, <code>Collection&lt;GenericTickType&gt;</code> and <code>Collection&lt;TickType&gt;</code> are two different classes and one is not assignable to the other.</p> <p>Now, if <code>TickType</code> is <em>castable</em> to <code>GenericTickType</code> (and they probably are if they are both enums, and assuming they share the same numeric values), you still cannot cast <code>Collection&lt;TickType&gt;</code> to <code>Collection&lt;GenericTickType&gt;</code>. There's no contra/co-variance in C# for most classes yet (coming in C# 4). But you could cast <em>each</em> <code>TickType</code> by doing something like this:</p> <pre><code>List&lt;GenericTickType&gt; list = new List&lt;GenericTickType&gt; { (GenericTickType)TickType.Price }; list.Add((GenericTickType)TickType.Price); // add more... Collection&lt;GenericTickType&gt;genericTicks = new Collection&lt;GenericTickType&gt;(list); </code></pre> <p>If you already have a <code>List&lt;TickType&gt;</code> and have access to C# 3.0 and LINQ, you can do this:</p> <pre><code>List&lt;TickType&gt; ticks = new List&lt;TickType&gt; { TickType.Price }; list.Add(TickType.Price); // add more... List&lt;GenericTickType&gt; castedList = ticks.Cast&lt;GenericTickType&gt;().ToList(); Collection&lt;GenericTickType&gt;genericTicks = new Collection&lt;GenericTickType&gt;(castedList); </code></pre> <p>This uses the LINQ <code>Cast&lt;T&gt;()</code> and <code>ToList&lt;T&gt;()</code> extension methods to cast <em>each</em> <code>TickType</code> in the original list to <code>GenericTickType</code> and creating a new <code>List&lt;GenericTickType&gt;</code> which is used to instantiate the <code>Collecion&lt;GenericTickType&gt;</code>. (I avoided using <code>var</code> so you could see the types in each step).</p>
 

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