std::derived_from
Defined in header <concepts> |
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template< class Derived, class Base > concept derived_from = std::is_base_of_v<Base, Derived> && std::is_convertible_v<const volatile Derived*, const volatile Base*>; |
(since C++20) |
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 behaviour is different to std::is_base_of when Base is a private or protected base of Derived.
Example
#include <concepts>
class A {};
class B: public A {};
class C: private A{};
int main() {
// 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
}
See also
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(C++11)
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checks if a type is derived from the other type (class template) |
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(C++11)(C++20)
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checks if a type can be converted to the other type (class template) |
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https://en.cppreference.com/w/cpp/concepts/derived_from
