std::derived_from
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Concepts library
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derived_from
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Exposition-only concepts
(C++20)
Defined in header
<concepts>
template< class Derived, class Base >
(since C++20)
concept derived_from =
std::is_base_of_v <Base, Derived> &&
The concept derived_from<Derived, Base> is satisfied if and only if Base is a class type that is either Derived or a public and unambiguous base of Derived, ignoring cv-qualifiers.
Note that this behavior is different to std::is_base_of when Base is a private or protected base of Derived.
[edit] Example
Run this code
#include <concepts> class A {}; class B : public A {}; class C : private A {}; // std::derived_from == true only for public inheritance or exact same class static_assert(std::derived_from<B, B> == true); // same class: true static_assert(std::derived_from<int, int> == false); // same primitive type: false static_assert(std::derived_from<B, A> == true); // public inheritance: true static_assert(std::derived_from<C, A> == false); // private inheritance: false // std::is_base_of == true also for private inheritance static_assert(std::is_base_of_v <B, B> == true); // same class: true static_assert(std::is_base_of_v <int, int> == false); // same primitive type: false static_assert(std::is_base_of_v <A, B> == true); // public inheritance: true static_assert(std::is_base_of_v <A, C> == true); // private inheritance: true int main() {}
[edit] References
- C++23 standard (ISO/IEC 14882:2024):
- 18.4.3 Concept
derived_from[concept.derived]
- 18.4.3 Concept
- C++20 standard (ISO/IEC 14882:2020):
- 18.4.3 Concept
derived_from[concept.derived]
- 18.4.3 Concept