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    <p>Why do you want to write an iterator class? The whole point of an iterator block is so you don't have to...</p> <p>i.e.</p> <pre><code>public IEnumerator&lt;T&gt; GetEnumerator() { int position = 0; // state while(whatever) { position++; yield return ...something...; } } </code></pre> <p>If you add more context (i,e, why the above can't work), we can probably help more.</p> <p>But if possible, avoid writing an iterator class. They are lots of work, and easy to get wrong.</p> <p>By the way, you don't really have to bother with <code>Reset</code> - it is largely deprecated, and shouldn't really ever be used (since it can't be relied to work for an arbitrary enumerator).</p> <p>If you want to consume an inner iterator, that is fine too:</p> <pre><code>int position = 0; foreach(var item in source) { position++; yield return position; } </code></pre> <p>or if you only have an enumerator:</p> <pre><code>while(iter.MoveNext()) { position++; yield return iter.Current; } </code></pre> <p>You might also consider adding the state (as a tuple) to the thing you yield:</p> <pre><code>class MyState&lt;T&gt; { public int Position {get;private set;} public T Current {get;private set;} public MyState(int position, T current) {...} // assign } ... yield return new MyState&lt;Foo&gt;(position, item); </code></pre> <p>Finally, you could use a LINQ-style extension/delegate approach, with an <code>Action&lt;int,T&gt;</code> to supply the position and value to the caller:</p> <pre><code> static void Main() { var values = new[] { "a", "b", "c" }; values.ForEach((pos, s) =&gt; Console.WriteLine("{0}: {1}", pos, s)); } static void ForEach&lt;T&gt;( this IEnumerable&lt;T&gt; source, Action&lt;int, T&gt; action) { if (source == null) throw new ArgumentNullException("source"); if (action == null) throw new ArgumentNullException("action"); int position = 0; foreach (T item in source) { action(position++, item); } } </code></pre> <p>Outputs:</p> <pre><code>0: a 1: b 2: c </code></pre>
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    1. USMarc Gravell
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    1. COI'm looking at the case of the internal enumerator "while(iter.MoveNext()) ... [etc]": aren't we leaking the 'iter' instance here ? The auto-generated outer enumerator wouldn't know 'iter' should be disposed, right ?
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    2. CO@toong if your iterator block takes out something IDisposable, then it should use a `using` statement - which will then be correctly cleaned up under most normal usage,
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