title: Partial class template specialisation for multiple types
body: <p>I have a class which allows for a vector to be created holding any type or class. However I'd like to add additional functionality for numerical types.</p>
  
  <pre><code>template &lt;&gt;
  class Vec&lt;double&gt; : public VecBase&lt;double&gt;
  {
      //  == METHODS ==
      public:
          //  -- Constructors &amp; Destructors --
          explicit Vec(const unsigned long long t_size);
          virtual ~Vec();
  
          //  -- Operators --
          friend Vec&lt;double&gt; operator+(const Vec&lt;double&gt;&amp;, const double);
  
          //  -- Methods --
          double sum();
  
  ... etc.
  </code></pre>
  
  <p>I have partially specialised the class template to allow overloading of mathematical operators for double specialisation. I'd now like to extend this specialisation to int as well, but rather than copy the specialisation replacing double with int, is there a way to add it into the specialisation list?</p>
  
  <p>That is, is there any way to allow for:</p>
  
  <pre><code>template&lt;&gt;
  class Vec&lt;double (or) int&gt;
  </code></pre>
  
  <p>Cheers!</p>