20
General utilities library
[utilities]
20.15
Metaprogramming and type traits
[meta]
20.15.5
Unary type traits
[meta.unary]
20.15.5.1
General
[meta.unary.general]
1
#
Subclause
[meta.
unary]
contains templates that may be used to query the properties of a type at compile time
.
2
#
Each of these templates shall be a
Cpp17UnaryTypeTrait
(
[meta.
rqmts]
) with a base characteristic of
true_type
if the corresponding condition is
true
, otherwise
false_type
.