Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
A customisation point that queries the value of a property.
constexpr unspecified query = unspecified;
The name query denotes a
customization point object. The expression boost::asio::query(E,
P)
for some subexpressions E
and P (with types T = decay_t<decltype(E)>
and Prop =
decay_t<decltype(P)>)
is expression-equivalent to:
is_applicable_property_v<T, Prop> is not a well-formed constant expression
with value true, boost::asio::query(E, P)
is ill-formed.
Prop::template static_query_v<T> if the expression Prop::template static_query_v<T>
is a well-formed constant expression.
(E).query(P) if the expression (E).query(P)
is well-formed.
query(E, P)
if the expression query(E, P) is a valid expression with overload
resolution performed in a context that does not include the declaration
of the query customization
point object.
boost::asio::query(E, P)
is ill-formed.
Header: boost/asio/query.hpp
Convenience header: boost/asio.hpp