Re: [boost] Library proposal - indexed_array

Le jeudi 02 juin 2022 à 11:00 +0200, Maximilian Riemensberger a écrit :

On 6/2/22 07:57, Julien Blanc via Boost wrote:

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The library looks very interesting.  I think I could be very useful for defining custom error codes (enums) and their mapping to custom error strings.  This is relatively simple with a std::array if the codes are contiguous and starting from 0.  Your library would make it as easy for arbitrary code values, like http codes. Very useful.

Thanks for your feedback. This is indeed a very good use case.

Is there a particular reason to require c++17? I guess some std::array features that got added? I would assume that it should be possible to make it compile under C++14 (maybe using some boost array) since most constexpr things should already be available there.

The first reason it requires C++17 is because this is what i am targetting at the moment. However, making it C++14-compliant would require a few changes: * the library use template auto syntax in several places, this allows writing indexed_array>. In C++14 one would need to write indexed_array>, or resort to macros. * it makes use of std::is_invokable to correctly disable the default aggregate constructor if given a safe_arg initializer list. This can be worked around (iirc is_invokable can be emulated in C++14) * it also makes use of std::apply for multi-dimensional indexing. Likewise, this can be emulated in C++14. * there are probably a few others that i'm missing. In short: it can be done, but sticking to C++17 avoided reimplementing several now-standard library features.

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If there is some interest, i'd like to propose it for inclusion in boost. So i'm looking for people who would endorse it.

I endorse it.

Thanks for sharing.

Thanks for your feedback, and thanks for endorsing the library. Regard, Julien