About feature and namespace selection

About feature and namespace selection

Boost.Application supports use of some features from std or boost.

This is handled by "application/config.hpp" config file.

The features that can be selected are:

• shared_ptr
• make_shared
• static_pointer_cast

From # in "std" selection or #<boost/shared_ptr.hpp>, #<boost/make_shared.hpp> in "boost" selection.

• unordered_map

From #<unordered_map> in "std" selection or #<boost/unordered_map.hpp> in "boost" selection.

• type_index

From # in "std" selection or #<boost/type_index.hpp> in "boost" selection.

User can force the selection using theses macros:

BOOST_APPLICATION_FEATURE_NS_SELECT_STD

In this case "std" are used, like:

• std::shared_ptr
• std::make_shared
• std::static_pointer_cast

Note that some of this features are available only on C++11, if your compiler don't support C++11 use boost.

BOOST_APPLICATION_FEATURE_NS_SELECT_BOOST

In this case "boost" are used, like:

• boost::shared_ptr
• boost::make_shared
• boost::static_pointer_cast

e.g:

#define BOOST_APPLICATION_FEATURE_NS_SELECT_BOOST
// -
#include <iostream>
#include <boost/application.hpp>
#include <boost/uuid/string_generator.hpp>
// -
using namespace boost;
// -
class myapp
{
public:
   // -
   myapp(application::context& context)
	  : context_(context)
   {
   }
   // -
   int operator()()
   {
	  boost::shared_ptr<application::args> args =
		 context_.find<application::args>();
	  if(args)
	  {
		 const std::vector<std::string> &arg_vector = args->arg_vector();
		 // only print args on screen
		 for(std::vector<std::string>::const_iterator it = arg_vector.begin(); 
			it != arg_vector.end(); ++it) {
			std::cout << *it << std::endl;
		 }
	  }
   // -
	  context_.find<application::wait_for_termination_request>()->wait();
	  return 0;
   }
private:
   application::context& context_;
};
// -
// main
// -
int main(int argc, char *argv[])
{   
   application::context app_context;
   myapp app(app_context);
   // -
   boost::uuids::string_generator gen;
   // -
   app_context.insert<application::limit_single_instance>(
	  boost::make_shared<application::limit_single_instance_default_behaviour>(
		 gen("{2F66E4AD-ECA5-475D-8784-4BAA329EF9F1}")));
   // -
   return application::launch<application::common>(app, app_context);
}

If any of this are not defined, the default behaviour of selection is "automatic detect" that will try use better option for current system, in this case the user can use "csbl" namespace provided by Application.

The "csbl" will select current system option automatically, e.g:

int main(int argc, char *argv[])
{  
   application::context app_context;
   myapp app(app_context);
   app_context.insert<application::args>(
	  application::csbl::make_shared<application::args>(argc, argv));
   return application::launch<application::common>(app, app_context);
}

If system auto select std, the "application::csbl::make_shared" will be "converted" to std::make_shared, if boost will be boost::make_shared