title: Printing bools with boost::format as symbolic values?
body: <p>How do I print boolean values with <code>boost::format</code> as symbolic values?</p>
  <p>Can this be done without <code>boost::io::group</code>? It seems that flags sent to the stream beforehand get retested:</p>
  <pre><code>#include &lt;iomanip&gt;
  #include &lt;iostream&gt;
  #include &lt;boost/format.hpp&gt;
  
  int main()
  {
    std::cout
      &lt;&lt; std::boolalpha
      &lt;&lt; true &lt;&lt; &quot; &quot;
      &lt;&lt; boost::format(&quot;%1% %2%\n&quot;)
           % true
           % boost::io::group(std::boolalpha, true)
      ;
  }
  </code></pre>
  <p>Output</p>
  <pre><code>true 1 true
  </code></pre>