title: Why is there not an std::is_struct type trait?
body: <p>I've seen that in order to check if a type <code>T</code> is a class I can use:</p>
  
  <pre><code>bool isClass = std::is_class&lt;T&gt;::value;
  </code></pre>
  
  <p>It returns true for both classes and structs. I know that in C++ they are almost the same thing, but I'd like to know why there's not a distinction between them in the type trait. Is it always useless to check this difference, or is there some more reason that I don't understand?</p>