ReadOnlyList as a combination of two lists
<p>I have two lists in my class and i want to expose one more list as a ReadOnlyCollectoin which is a combination of the two lists.</p>

<p>I am looking for the best way of achieving this. So far i have two options</p>

<p>Option #1</p>

<pre><code>   public ReadOnlyCollection&lt;Item&gt; AllItems
    {
        get
        {
            var list = new List&lt;Item&gt;();
            list.AddRange(List1);
            list.AddRange(List2);
            return list.AsReadOnly();

        }
    }
</code></pre>

<p>Option #2</p>

<p>Make my two lists ObservableCollections and everytime they are modified, modify a third private list.
and then expose the third list as ReadOnlyCollection.</p>

<p>May be I missing something trivial here. There has to be a better way of achieving this.</p>
