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    copied!<p>It's not difficult to roll your own <code>ReadOnlyDictionary&lt;K,V&gt;</code> wrapper class. Something like this:</p> <pre><code>public sealed class ReadOnlyDictionary&lt;TKey, TValue&gt; : IDictionary&lt;TKey, TValue&gt; { private readonly IDictionary&lt;TKey, TValue&gt; _dictionary; public ReadOnlyDictionary(IDictionary&lt;TKey, TValue&gt; dictionary) { if (dictionary == null) throw new ArgumentNullException("dictionary"); _dictionary = dictionary; } public bool ContainsKey(TKey key) { return _dictionary.ContainsKey(key); } public int Count { get { return _dictionary.Count; } } public IEnumerator&lt;KeyValuePair&lt;TKey, TValue&gt;&gt; GetEnumerator() { return _dictionary.GetEnumerator(); } public ICollection&lt;TKey&gt; Keys { get { return _dictionary.Keys; } } public bool TryGetValue(TKey key, out TValue value) { return _dictionary.TryGetValue(key, out value); } public ICollection&lt;TValue&gt; Values { get { return _dictionary.Values; } } public TValue this[TKey key] // Item { get { return _dictionary[key]; } } #region IDictionary&lt;TKey, TValue&gt; Explicit Interface Implementation void IDictionary&lt;TKey, TValue&gt;.Add(TKey key, TValue value) { throw new NotSupportedException("Dictionary is read-only."); } bool IDictionary&lt;TKey, TValue&gt;.Remove(TKey key) { throw new NotSupportedException("Dictionary is read-only."); } TValue IDictionary&lt;TKey, TValue&gt;.this[TKey key] // Item { get { return _dictionary[key]; } set { throw new NotSupportedException("Dictionary is read-only."); } } #endregion #region ICollection&lt;T&gt; Explicit Interface Implementation void ICollection&lt;KeyValuePair&lt;TKey, TValue&gt;&gt;.Add(KeyValuePair&lt;TKey, TValue&gt; item) { throw new NotSupportedException("Collection is read-only."); } void ICollection&lt;KeyValuePair&lt;TKey, TValue&gt;&gt;.Clear() { throw new NotSupportedException("Collection is read-only."); } bool ICollection&lt;KeyValuePair&lt;TKey, TValue&gt;&gt;.Contains(KeyValuePair&lt;TKey, TValue&gt; item) { return _dictionary.Contains(item); } void ICollection&lt;KeyValuePair&lt;TKey, TValue&gt;&gt;.CopyTo(KeyValuePair&lt;TKey, TValue&gt;[] array, int arrayIndex) { _dictionary.CopyTo(array, arrayIndex); } bool ICollection&lt;KeyValuePair&lt;TKey, TValue&gt;&gt;.IsReadOnly { get { return true; } } bool ICollection&lt;KeyValuePair&lt;TKey, TValue&gt;&gt;.Remove(KeyValuePair&lt;TKey, TValue&gt; item) { throw new NotSupportedException("Collection is read-only."); } #endregion #region IEnumerable Explicit Interface Implementation IEnumerator IEnumerable.GetEnumerator() { return ((IEnumerable)_dictionary).GetEnumerator(); } #endregion } </code></pre> <p>If you're using C#3 or later then you could knock-up a matching <code>AsReadOnly</code> extension method too:</p> <pre><code>public static class ReadOnlyDictionaryHelper { public static ReadOnlyDictionary&lt;TKey, TValue&gt; AsReadOnly&lt;TKey, TValue&gt;(this IDictionary&lt;TKey, TValue&gt; dictionary) { var temp = dictionary as ReadOnlyDictionary&lt;TKey, TValue&gt;; return temp ?? new ReadOnlyDictionary&lt;TKey, TValue&gt;(dictionary); } } </code></pre> <p>And then return the read-only wrapper from your property:</p> <pre><code>// in C#2 return new ReadOnlyDictionary&lt;string, OfTable&gt;(_folderData); // in C#3 or later return _folderData.AsReadOnly(); </code></pre>
 

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