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copied!<p>Define few typedefs as:</p> <pre><code>typedef typename DataStructure::reference reference; typedef typename DataStructure::const_reference const_reference; typedef reference (DataStructure::*top_type)(); //non-const version typedef const_reference (DataStructure::*ctop_type)() const;//const version </code></pre> <p>then use whatever you need it. </p> <p>In the posted code, you need const version, so write this:</p> <pre><code>mem_fun( static_cast<ctop_type>(&DataStructure::top )) </code></pre> <p>The casting helps compiler to choose the version you intend to use.</p> <p>By the way, in C++11, <code>std::mem_fun</code> is <strong>deprecated</strong>. And it has added another function called <code>std::mem_fn</code>. Notice the difference in the spelling. See this topic for details:</p> <ul> <li><a href="https://stackoverflow.com/questions/11680807/stdmem-fun-vs-stdmem-fn">std::mem_fun vs std::mem_fn</a></li> </ul> <hr> <p>What you need is called <code>std::bind</code>, not <code>std::mem_fun</code> (or <code>std::mem_fn</code>) :</p> <p>It works now:</p> <ul> <li><a href="http://stacked-crooked.com/view?id=88f50b5f7e3e4d1e94de019640326075-18aa934a8d82d638dde2147aa94cac94" rel="nofollow noreferrer">Online Demo</a></li> </ul> <p>The way you're calling <code>getter</code> suggests that you need <code>std::bind</code> because you're invoking <code>getter</code> like this:</p> <pre><code>auto const current = getter(); </code></pre> <p>That is an error if <code>getter</code> is an object returned from <code>std::mem_fun</code>, in which case it should be invoked like this:</p> <pre><code>auto const current = getter(&ds); </code></pre> <p>See this demo:</p> <ul> <li><a href="http://stacked-crooked.com/view?id=d764365d5460991ace4d8f9ebe6b685f-18aa934a8d82d638dde2147aa94cac94" rel="nofollow noreferrer">Online Demo</a></li> </ul> <p>Or if you simply pass the pointer-to-member, then you invoke as:</p> <pre><code>auto const current = (ds.*getter)(); </code></pre> <p>See : <a href="http://stacked-crooked.com/view?id=aa7c828018df318ab3b6d53b75ecb538-18aa934a8d82d638dde2147aa94cac94" rel="nofollow noreferrer">Online Demo</a></p> <p>Compare all three. See the differences!</p> <p>Hope that helps.</p>

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