oktal / result Goto Github PK

Right now this library contains two versions of Result: one with normal Ok enum and another with void one.

It may be a short-term convenience for callers (simple Ok() suffices if there's nothing of value to return). However:

• Essentially there are two versions of each struct and function: double effort for maintenance
• void is an incomplete type and thus presents distant problems for callers (like #6)

Which begs a question: do we really need special casing for void? My proposal is:

• Bar void from Ok
• Provide a dummy type alias for empty tuple (std::tuple<>) / empty struct (struct {}) and relevant Ok (using OK = Ok<Dummy>)
• Include special macro for convenient lambda creation (e.g. DUMMY_CB for [&](const Dummy&)

This will lead to a closer-to-Rust Ok construction in the form of OK({}) and eliminate any void-related template issues.

TRY macro fails when we have void associated with Ok (and rightfully so, since assigning void makes no sense).

Perhaps a separate macro for simple error propagation and static_assert for more informative failure?

in expansion of macro 'TRY'

result.h:631:14: note: candidate: template<class U> const U& details::Storage<void, E>::get() const [with U = U; E = int]
     const U& get() const {
              ^~~
result.h:631:14: note:   template argument deduction/substitution failed:
result.h: In substitution of 'template<class U> const U& details::Storage<void, E>::get() const [with U = void]':
result.h:631:14: error: forming reference to void
result.h:636:8: note: candidate: template<class U> U& details::Storage<void, E>::get() [with U = U; E = int]
     U& get() {
        ^~~
result.h:636:8: note:   template argument deduction/substitution failed:
result.h: In substitution of 'template<class U> U& details::Storage<void, E>::get() [with U = void]':
result.h:636:8: error: forming reference to void

Shouldn't a simple return false; in the end fix it?

Currently there is no mention of how you wish to license this software. Therefore, technically (under some interpretations), it is in violation of copyright law for others to make a copy.

I'd think it'd be nice for the community if you explicitly set the license.

For a single-file header, I'd recommend a very permissive license, such as the UNLICENSE or MIT.

The project looks good, thanks!

Currently several functions will call std::terminate on failure. It would be beneficial to allow users to customize this behavior, or possibly switch to using an exception (e.g., illegal state) so the user can catch it and then decide what to do next. While this would not be ideal, there may be circumstances where terminating is extremely inappropriate as there won't be a chance to do a proper cleanup.

Is it still possible to use andThen/bind ?
"then" is not what i'm looking for (i think).

template<typename R, typename E>
class
#if __cplusplus >= 201703L
[[nodiscard]]
#endif
Result {

};

This is c++17 feature and will show warning if you will ignore the Result

Could you add an example for mapError function usage?

It seems the only way to retrieve the value within the Err is to call through to the storage struct. In Rust, this is done with a match, but there's nothing exactly like that in C++. Could you add an unwrapErr or add documentation on the proper way to extract values like you would with match in Rust?

namespace concept is invalid in C++20-enabled compilers because concept is then a keyword.