title: using custom deleter with unique_ptr
body: <p>With shared_ptr you can use a custom deleter, like:</p>
  
  <pre><code>auto fp = shared_ptr&lt;FILE&gt;( fopen("file.txt", "rt"), &amp;fclose );
  fprintf( fp.get(), "hello\n" );
  </code></pre>
  
  <p>and this will remember to <code>fclose</code> the file regardless of how the function exits. <br>
  However, it seems a bit overkill to refcount a local variable, so I want to use <code>unique_ptr</code>:</p>
  
  <pre><code>auto fp = unique_ptr&lt;FILE&gt;( fopen("file.txt", "rt"), &amp;fclose );
  </code></pre>
  
  <p>however, that does not compile.</p>
  
  <p>Is this a defect? Is there a simple workaround? Im I missing something trivial?</p>