Move-assign a posix::basic_stream_descriptor
from
a descriptor of another executor type.
template< typename Executor1> constraint< is_convertible< Executor1, Executor >::value, basic_stream_descriptor & >::type operator=( basic_stream_descriptor< Executor1 > && other);
This assignment operator moves a descriptor from one object to another.
The other posix::basic_stream_descriptor
object from which the move will occur.
Following the move, the moved-from object is in the same state as if
constructed using the basic_stream_descriptor(const executor_type&)
constructor.