On 30.01.2017 11:19, Niall Douglas wrote:
I am truly hoping that this will be the last time I ask for feedback on Outcome's tutorial as this is the third complete rewrite. Many thanks for all the feedback so far, this Mk. III tutorial wouldn't look like this without all your help.
Just some semi-random comments from a "plain" Boost user, who also read the initial version of the docs. The current form is much better than the initial version. It was easier to skip the parts that I do not care much about, and easier to follow what the goal of the library was. As someone who hasn't read anything about expected<T,E> before, it was nice to have a section on it. I overall liked the code examples, they worked much better for me than the previous ones. However I do think the name "Tutorial" is a bit of a misnomer, and the parts A, B and C should be renamed to "Background", "Rationale" and "Introduction" respectively (or something similar). Most of part C is introducing the API, and the full tutorial bits, when ready, really should stand out a bit more compared to the current A, B and C sections. In part B I think you should drop the inlined list of std:errc members, instead linking to it somewhere. Then you could simply write: "The third reason is that the C++ 11 standard library already provides an enum of the most common error codes for you. It's called std::errc and it has the standard POSIX error codes. Most of the time you'll find that whatever custom error code domain you may want to write can be adequately covered by std::errc. In fact, let's try it:" The list, while a useful reference, adds to the "wall of text" feeling that part B already suffers a bit from. Going back to the start, I think rephrasing the initial portion of the description section to focus on Outcome rather than expected<T, E> would be beneficial. As it reads now, I still come away from this thinking it's a helper library to expected<T, E>, rather than something that could very well be used on its own. Just an example: "This is the Outcome library. It' a Boost C++ 14 library intended for ultra-lightweight error handling in large C++ codebases, providing a more expressive and type safe alternative to integer error codes or enums. Unlike alternative implementations, it works perfectly with exceptions and RTTI disabled and is thus suitable for low-latency/games/finance/SG14 users. One could view Outcome as a minimum overhead universal outcome transport mechanism for C++, hence being named "Outcome". The Outcome library provides an implementation of expected<T, E> (which is on the C++ 20 standardisation track), with the expected<T, E> refinements outcome<T> and result<T>." Now I'm just a n00b, but I get worried about the raw char*'s everywhere. I know you're aiming for maximum speed, but couldn't the interface have std:string overloads as a safer alternative? At least for things like error_code_extended::extended_message(). I don't generally care much for the brute-force performance of my error handling code, it's not the hot path. Personally I like that you've removed the word "monad" for most of the documentation. It's one of those concepts I sorta know what is, but I still have to do a web search each time just to remind me. Though in part C one is introduced to monad_error and friends. Now, _I don't mind this_, however I think it would be nice to have a _footnote_ here to quickly explain where the name comes from, with a link to some page with more info on monads. Anyway, I now got a much better impression of what this library is about than the initial version of the docs. It also presented Outcome as a useful and interesting library, and as something I would want to try. Cheers - Asbjørn