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POC#: Semantics for generics?
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  1. POC#: Semantics for generics?
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    copied!<p>I have a list:</p> <pre><code>private readonly IList&lt;IList&lt;GameObjectController&gt;&gt; removeTargets; private readonly IList&lt;IList&lt;GameObjectController&gt;&gt; addTargets; </code></pre> <p><code>PickUp</code> inherits from <code>GameObjectController</code>. But when I try this:</p> <pre><code>public IList&lt;PickUp&gt; Inventory // ... gameObjectManager.MoveFromListToWorld(this, user.Model.Inventory); // ... // This queues everything up to be removed, until ProcessMoves...() is called public void MoveFromWorldToList(GameObjectController removedFromWorld, IList&lt;GameObjectController&gt; addTarget) { toBeRemoved.Add(removedFromWorld); addTargets.Add(addTarget); } // ... /// &lt;summary&gt; /// Removes all the GameObjects on which removal is requested from the world. /// &lt;/summary&gt; public void ProcessMovesFromListToWorld() { for (int i = 0; i &lt; toBeAdded.Count; i++) { GameObjectController moved = toBeAdded[i]; addGameObjectToWorld(moved); if (removeTargets[i] != null) { removeTargets[i].Remove(moved); } } toBeAdded.Clear(); removeTargets.Clear(); } </code></pre> <p>I get a compiler error:</p> <blockquote> <p>cannot convert from 'System.Collections.Generic.IList&lt;PickUp>' to 'System.Collections.Generic.IList&lt;GameObjectController>'</p> </blockquote> <p>Why does this occur? Shouldn't this be fine, since <code>PickUp</code> is a subclass of <code>GameObjectController</code>? Do I need something like Java's <code>Map&lt;E extends GameObjectController&gt;</code>? </p> <p>Earlier, I was having a similar problem, where I was trying to implicitly cast <code>inventory</code> from an <code>IList</code> to an <code>ICollection</code>. Is this the same problem?</p>
 

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