...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Determine if an io_service contains a specified service type.
template< typename Service> friend bool has_service( io_service & ios);
This function is used to determine whether the io_service contains a service object corresponding to the given service type.
The io_service object that owns the service.
A boolean indicating whether the io_service contains the service.