title: Which type to use for callable to std::bind
body: <p>in a function I need to pass as argument a callable for std::bind.
  What is the correct type/template I should use?</p>
  
  <pre><code>void foo(std::function&lt;void(KnownType)&gt; function, WhatShouldThisBe target)
  {
      std::bind(function, target);
  }
  </code></pre>
  
  <p>The intended use would then be:</p>
  
  <pre><code>std::shared_ptr&lt;SomeType&gt; bar = std::make_shared&lt;SomeType&gt;();
  foo(&amp;SomeType::function, bar);
  </code></pre>