Viktor Sehr wrote:
I'm not a reviewer, but I'd like to add a note on the interface:
I think boost::charconv should add one convenience function as follows:
// Returns std::nullopt on error template <typename NumberType> std::optional<NumberType> boost::charconv::to_number(const std::string_view& sv) noexcept;
This throws away the error code; it should return (if we stick to standard facilities) std::expected<NumberType, std::error_code> However, std::expected is C++23 (std::optional is "only" C++17, same as std::from_chars.) Expressed with our facilities it would return boost::system::result<NumberType>. Interestingly, returning a boost::system::error_code instead of errc could in principle have the additional benefit of returning the source location where the error originated (this tends to be pretty useful when debugging failures.) But for that, the implementation needs to be refactored to return error_code instead of errc, only dropping it at the from_chars level. Also interestingly, std::from_chars used to return std::error_code, but was changed to return std::errc to avoid a dependency on <system_error> and therefore <string>. One issue with this interface is that we're again losing the ability to distinguish between the four possible ERANGE failures, as now a return value is no longer available on error. Although I suppose we can define our own erange_category with four values there, all equivalent to ERANGE from the generic category.