...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
An argument placeholder, for use with boost::bind(), that corresponds to
the signal_number argument of a handler for asynchronous functions such as
boost::asio::signal_set::async_wait
.
unspecified signal_number;
Header: boost/asio/placeholders.hpp
Convenience header: boost/asio.hpp