template< typename Service> Service & use_service( execution_context & e);
This function is used to locate a service object that corresponds to the
given service type. If there is no existing implementation of the service,
then the execution_context
will create
a new instance of the service.
The execution_context
object
that owns the service.
The service interface implementing the specified service type. Ownership of the service interface is not transferred to the caller.