</span><span class=identifier>k</span><span class=special>; </span><span class=comment>// where i, j, and k are ints</span></font></code></pre>
<p>Expression templates yield an endless supply of types. Without the <a href="rule.html">rule</a>, 
  there is no easy way to do this in C++ if <tt>i</tt>, <tt>j</tt> and <tt>k</tt> 
  are Spirit parsers:</p>
<pre><code><font color="#000000"><span class=comment>    </span><span class=special>&lt;</span><span class=identifier>what_type???</span><span class=special>&