std::default_initializable
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default_initializable
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Exposition-only concepts
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Defined in header
<concepts>
template< class T >
(since C++20)
concept default_initializable = std::constructible_from <T> && requires { T{}; } &&
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.
[edit] Possible implementation
template<class T> concept default_initializable = std::constructible_from <T> && requires { T{}; ::new T; };
[edit] References
- C++23 standard (ISO/IEC 14882:2024):
- 18.4.12 Concept
default_initializable[concept.default.init]
- 18.4.12 Concept
- C++20 standard (ISO/IEC 14882:2020):
- 18.4.12 Concept
default_initializable[concept.default.init]
- 18.4.12 Concept
[edit] See also
(C++20)
(concept) [edit]