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A customisation point that queries the value of a property.
constexpr unspecified query = unspecified;
The name query denotes a
customization point object. The expression 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, 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.
asio::query(E, P)
is ill-formed.
Header: asio/query.hpp
Convenience header: asio.hpp