title: C++ Function Pointer as Default Template Argument
body: <p>how do I write a function pointer as default template argument, I'am guessing to write it like this:</p>
  
  <pre><code>template&lt;typename R,
           typename A,
           typename F=R (*PF)(A)&gt; 
  class FunctionPtr { ...
  </code></pre>
  
  <p>my question is, </p>
  
  <p>1.is it possible?</p>
  
  <p>2.if it is and my guess code above is correct, what the purpose of <code>PF</code> here? do I need this?</p>