std::default_initializable
Defined in header <concepts> | ||
|---|---|---|
template< class T >
concept default_initializable = std::constructible_from<T> && requires { T{}; } &&
/* T t; is well-formed, see below */;
| (since C++20) |
The default_initializable concept checks whether variables of type T can be
-
value-initialized (i.e., whether
T()is well-formed); -
direct-list-initialized from an empty initializer list (i.e., whether
T{}is well-formed); and -
default-initialized (i.e., whether
T t;is well-formed).
Access checking is performed as if in a context unrelated to T. Only the validity of the immediate context of the variable initialization is considered.
Possible implementation
template<class T>
concept default_initializable =
std::constructible_from<T> &&
requires { T{}; ::new T; };
|
References
- C++23 standard (ISO/IEC 14882:2024):
- 18.4.12 Concept
default_initializable[concept.default.init] - C++20 standard (ISO/IEC 14882:2020):
- 18.4.12 Concept
default_initializable[concept.default.init]
See also
|
(C++20) | specifies that a variable of the type can be constructed from or bound to a set of argument types (concept) |
|
(C++11)(C++11)(C++11) | checks if a type has a default constructor (class template) |
|
(C++26)(C++26)(C++26) | checks if reflected type has a default constructor (function) |
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