title: boost::PO and cannot bind to ‘std::basic_ostream<char>&&’
body: <p>I'm writing a program with use of boost::program_option but I can't use one of its feature:</p>
  
  <pre><code> po::options_description desc("Allowed options");
  desc.add_options()
      ("include-path,I", po::value&lt; std::vector&lt;std::string&gt; &gt;(), "include path");
  
  po::variables_map vm;
  po::store(po::parse_command_line(argc, argv, desc), vm);
  po::notify(vm);
  
  if (vm.count("include-path"))
  {
      std::cout &lt;&lt; "Include paths are: " 
           &lt;&lt; vm["include-path"].as&lt; std::vector&lt;std::string&gt; &gt;() &lt;&lt; "\n";
  }
  </code></pre>
  
  <p>It's pretty the same as in boost.tutorial (<a href="http://www.boost.org/doc/libs/1_57_0/doc/html/program_options/tutorial.html" rel="nofollow noreferrer">http://www.boost.org/doc/libs/1_57_0/doc/html/program_options/tutorial.html</a>)</p>
  
  <p>I Get such error:
  error: cannot bind ‘std::basic_ostream’ lvalue to ‘std::basic_ostream&amp;&amp;’
  std::cout &lt;&lt; "Include paths are: " &lt;&lt; vm["include-path"].as>() &lt;&lt; std::endl; </p>
  
  <p>I've read some topics such as:
  <a href="https://stackoverflow.com/questions/13347530/error-cannot-bind-stdbasic-ostreamchar-lvalue-to-stdbasic-ostreamchar">error: cannot bind ‘std::basic_ostream’ lvalue to ‘std::basic_ostream&amp;&amp;’</a>
  <a href="https://stackoverflow.com/questions/10651161/overloading-operator-cannot-bind-lvalue-to-stdbasic-ostreamchar">Overloading operator&lt;&lt;: cannot bind lvalue to ‘std::basic_ostream&amp;&amp;’</a></p>
  
  <p>But I don't see connection with my problem.
  My platform: Fedora 20, Gcc 4.8.3, boost_1_57_0, I'm using -std=c++11 flat to compile code.</p>