id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
10393	Add begin/end specialization for optional<T> type	khimru@…	Fernando Cacciola	"optional<T> could be used in many places as if it was just T, but, since C++ does not apply two levels of constructions one could not use this natural looking construct for optional containers:

if (opt_container) {
  for (auto& element : opt_container) {
     ...
  }
}

Simple specialization of begin()/end() functions could solve this problem:

namespace std {

template<class T>
inline auto
begin(const boost::optional<T>& opt) -> decltype(opt.get().begin()) {
 return opt.get().begin();
}

template<class T>
inline auto
begin(boost::optional<T>& opt) -> decltype(opt.get().begin()) {
  return opt.get().begin();
}

template<class T>
inline auto
end(const boost::optional<T>& opt) -> decltype(opt.get().end()) {
  return opt.get().end();
}

template<class T>
inline auto
end(boost::optional<T>& opt) -> decltype(opt.get().end()) {
  return opt.get().end();
}

}
"	Feature Requests	new	Boost 1.57.0	optional	Boost 1.56.0	Cosmetic		optional, for, begin, end