#include <cassert>
#include <iostream>
#include <string>
#include <type_traits>

template<class> constexpr bool supported = false;
template<class T>
std::string describe(const T& x) {
    using U = std::remove_cv_t<std::remove_reference_t<T>>;
    if constexpr (std::is_integral_v<U>) {
        return "integer:" + std::to_string(x);
    } else if constexpr (std::is_same_v<U, std::string>) {
        return "text:" + std::to_string(x.size());
    } else {
        static_assert(supported<U>, "requires integer or string");
    }
}

int main() {
    const int n = 7;
    std::string s = "abc";
    assert(describe(n) == "integer:7");
    assert(describe(s) == "text:3");
    std::cout << describe(n) << ' ' << describe(s) << '\n';
}