Why there are no template functions something like:
C++17 has such generic string to number function, but named differently. They went with std::from_chars, which is overloaded for all numeric types.
As you can see, the first overload is taking any integer type as an output parameter and will assign the value to it if possible.
It can be used like this:
template<typename Numeric>
void stuff(std::string_view s) {
auto value = Numeric{};
auto [ptr, error] = std::from_chars(s.data(), s.data() + s.size(), value);
if (error != std::errc{}) {
// error with the conversion
} else {
// conversion successful, do stuff with value
}
}
As you can see, it can work in generic context.