The following code example is taken from the book
C++20 - The Complete Guide
by Nicolai M. Josuttis,
Leanpub, 2021
The code is licensed under a
Creative Commons Attribution 4.0 International License.
// raw code
#include <type_traits> // for std::is_convertible_v<>
template<typename T>
class Wrapper {
T value;
public:
template<typename U>
explicit(!std::is_convertible_v<U, T>)
Wrapper(const U& val)
:value{val} {
}
//...
};