gistfile1.cpp

          // pull layers from query string
          boost::optional<std::string> layer_string = get_layer_string():
          if (layer_string)
          {
              std::clog << "filtering layers...\n";
              // convert comma separated layers to vector
              std::vector<std::string> layer_names = parse_layer_string(*layer_string);
              
              // for each map layer object
              BOOST_FOREACH ( layer const& lyr, map_.layers() )
              {
                  bool requested = false;
                  // figure out if it was requested and either
                  // set active (status = on) or disable
                  BOOST_FOREACH ( std::string & lyr_name, layer_names )
                  {
                      
                      if (lyr.name() == lyr_name)
                      {
                          requested = true;
                      }
                  }
                  lyr.setActive(requested);
              }
          }