Re: [boost] Boost.Charconv review runs January 15th - 25th, 2024

Dominique Devienne wrote:

On Wed, Jan 31, 2024 at 1:38 PM Peter Dimov via Boost mailto:boost@lists.boost.org > wrote:

Viktor Sehr wrote:

...

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

But sometimes that's all you want. That's kinda the point from Viktor I guess.

It's actually never what you want the way from_chars is specified, because 0.000[more 0...]001 fails with ERANGE, whereas 1.000[same 0...]001 succeeds and returns 1.0. I don't really know of a use case where this is what one wants.

Not that an `expected` or `outcome` return type is bad; but it is more complex.

It's not any more complex for the user; the interface is the same as optional's if you don't need the error. Returning `optional` is almost always a design mistake.