title: How to use explicit template instantiation to reduce compilation time?
body: <p>It was suggested to use explicit template instantiation to reduce compilation time. I am wondering how to do it. For example</p>
  <pre><code>// a.h
  template&lt;typename T&gt; class A {...};
  template class A&lt;int&gt;; // explicit template instantiation  to reduce compilation time
  </code></pre>
  <p>But in every translation unit where a.h is included, it seems <code>A&lt;int&gt;</code> will be compiled. The compilation time is not reduced. How to use explicit template instantiation  to reduce compilation time?</p>