Re: [boost] Library proposal - indexed_array

On 6/2/22 13:30, Julien Blanc wrote:

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

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

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.

I see. The first one is definitely a language limitation. But I guess it's mostly an inconvenience to the users of the library if they are on C++14. The other ones as far as I can see have counterparts in boost that would work in C++14 as well. So I guess it could be done without too much hassle if there is a need and the library would be included in boost. Either way, it's very useful regardless of the std version details. Best, Max