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    <p>I suggest using boost range (algorithms &amp; adaptors) for ease of use, you'd write:</p> <pre><code>boost::copy( data | transformed(makeT) | filtered(validate) /* | indirected */, std::back_inserter(queue)); </code></pre> <p>Here is a complete working example of that:</p> <pre><code>#include &lt;boost/range.hpp&gt; #include &lt;boost/range/adaptors.hpp&gt; #include &lt;boost/range/algorithm.hpp&gt; #include &lt;boost/optional.hpp&gt; #include &lt;vector&gt; #include &lt;deque&gt; typedef boost::optional&lt;int&gt; T; typedef std::deque&lt;T&gt; Q; static T makeT(int i) { if (i%2) return T(); else return i; } static bool validate(const T&amp; optional) { return (bool) optional; // select the optional that had a value set } int main() { static const int data[] = { 1,2,3,4,5,6,7,8,9 }; Q q; using boost::adaptors::filtered; using boost::adaptors::transformed; // note how Boost Range elegantly supports an int[] as an input range boost::copy(data | transformed(makeT) | filtered(validate), std::back_inserter(q)); // demo output: 2, 4, 6, 8 printed for (Q::const_iterator it=q.begin(); it!=q.end(); ++it) { std::cout &lt;&lt; (*it? "set" : "unset") &lt;&lt; "\t" &lt;&lt; it-&gt;get_value_or(0) &lt;&lt; std::endl; } return 0; } </code></pre> <p><strong>Update</strong></p> <p>With a little help from this answer: <a href="https://stackoverflow.com/questions/6123327/use-boostoptional-together-with-boostadaptorsindirected">Use boost::optional together with boost::adaptors::indirected</a></p> <p>I now include an elegant demonstration of using the <code>indirected</code> range adaptor as well for immediate output of the queue (dereferencing the optionals):</p> <blockquote> <p><sub>Note that for (smart) pointer types there would <em>obviously</em> be no need to provide the <code>pointee&lt;&gt;</code> specialisation. I reckon this is by design: <em><a href="http://www.boost.org/doc/libs/1_47_0/libs/optional/doc/html/boost_optional/development.html#id555831" rel="nofollow noreferrer"><code>optional&lt;&gt; is not, and does not model, a pointer</code></a></em></sub></p> </blockquote> <pre><code>#include &lt;boost/range.hpp&gt; #include &lt;boost/range/adaptors.hpp&gt; #include &lt;boost/range/algorithm.hpp&gt; #include &lt;boost/optional.hpp&gt; namespace boost { template&lt;typename P&gt; struct pointee&lt;optional&lt;P&gt; &gt; { typedef typename optional&lt;P&gt;::value_type type; }; } typedef boost::optional&lt;int&gt; T; static T makeT(int i) { return i%2? T() : i; } static bool validate(const T&amp; optional) { return (bool) optional; } int main() { using namespace boost::adaptors; static int data[] = { 1,2,3,4,5,6,7,8,9 }; boost::copy(data | transformed(makeT) | filtered(validate) | indirected, std::ostream_iterator&lt;int&gt;(std::cout, ", ")); } </code></pre>
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    1. CONice, I didn't know about adaptors, the pipeline syntax looks really nifty.
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    2. COedited: showing the `indirected` range adaptor now as well, to dereference the optionals on the fly
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    3. COcould we, therefore, use such syntax `boost::copy(data | transformed(makeT) | filtered(validate) | indirected, std::ostream_iterator<int>(std::cout, ", "));` ? (I wonder if we could skip the validate phase, ie if indirected is smart enough to handle null pointers).
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