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Reflection for C++26

(isocpp.org)
196 points svlasov | 2 comments | 30 Jun 24 11:26 UTC | HN request time: 0.034s | source
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stefanos82 ◴[01 Jul 24 22:41 UTC] No.40851614[source]▶
Can I ask a naive question that consists of two parts and please don't flame me? lol

  * What type of problems static reflection could solve, in general?
  * Are there specific cases and / or situations where static reflection could resolve such case, even simplify an unnecessary complexity?
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bdd8f1df777b ◴[02 Jul 24 02:55 UTC] No.40853159[source]▶
What I commonly need is JSON serialization/parsing directly with structs.
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beached_whale ◴[02 Jul 24 05:26 UTC] No.40853788[source]▶
They exist, for instance https://github.com/beached/daw_json_link , uses mappings of JSON <-> class members/construction. It handles a bunch of types out of the box and allows custom types to be mapped. Also, it integrates with some of the reflection like libraries out there now(Boost.Describe/Boost.PFR) and will be trivial to add C++26 static reflection when available.

Because the library doesn’t need to allocate unless the underlying types being parsed to do, it has been constexpr since C++17 too.

A bunch of people have used libraries that use macros for reflection like or PFR to integrate other C++ JSON Libraries too.

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1. bdd8f1df777b ◴[03 Jul 24 02:05 UTC] No.40862169{3}[source]▶
Without static reflection, we need to write a lot of boilerplate code, and those boilerplate is not guaranteed to stay in sync with the struct definition. That is why static reflection is sorely needed.
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2. beached_whale ◴[03 Jul 24 05:30 UTC] No.40862991[source]▶
Even static reflection isn’t a panacea and we have it now the libraries like PFR that give us a reference and name of each member for aggregates. But this is the same problem for anything else using those types too. For non-aggregates we need reflection or some manual library.

I am not disagreeing, just more saying what we have now.