id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
10552	Add make_valid_future	viboes	viboes	"Some functions require that the future are valid.

The needs to check for the validity before using these futures.

{{{
if (fut.valid()) {
  auto x = fut.then(fct);
}
if (f1.valid() && f2.valid()) {
  auto x = when_all(f1, f2);
}

}}}

An alternative is to provide a make_valid_future function that ensure that the result is valid. If the input future is valid it return the same future, otherwise it sets an exception future_error, and the corresponding error condition would be std::future_errc::no_state.

In this way the user can always use it as  


{{{
auto x = make_valid_future(fut).then(fct);

auto y = when_all(make_valid_future(f1), make_valid_future(f2));
}}}
"	Feature Requests	closed	Boost 1.57.0	thread	Boost 1.56.0	Problem	fixed