Serialization is the canonical example. Being able to turn

    struct MyStruct {
      int val = 42;
      string name = "my name";
    };

into

    {
      "val": 42, // if JSON had integers, and comments of course
      "name": "my name",
    }

is incredibly powerfuly. If reflection supported attributes (i can't believe it shipped without, honestly), then you could also mark members as [[ignore]] and skip them.

▲ SuperV1234 an hour ago | parent | next [-]

You can achieve that since C++20 (or C++17 if you don't care about the member names). E.g. https://www.linkedin.com/posts/vittorioromeo_cpp-gamedev-ref...

(The link above shows ImGui generation, but the same exact logic can be applied for serialiation to JSON/YAML/whatever.)

▲

maccard 12 minutes ago | parent [-]

Sure, but

> The magic sauce? Boost.PFR! An incredibly clever library that enables reflections on aggregates, even in C++17.

That's not vanilla C++!

	▲	SuperV1234 a minute ago \| parent [-]
		...so what? It's just a header you have to #include.

▲ bluGill an hour ago | parent | prev [-]

It is powerful, but I'm not sure it is a good idea. Other languages have it, and there is lots of experience in all the ways things go wrong in the real world. I'm inclined to say you should hand write this code because eventually you will discover something weird anyway.

	▲	maccard 8 minutes ago \| parent \| next [-]
		I disagree. Rust's defacto default is serde, golang comes with batteries included, dotnet/java have had it for _years_, and all the dynamic languages do it.
	▲	electroly an hour ago \| parent \| prev \| next [-]
		Can you give an example of a language ecosystem that went with reflection-based JSON serialization/deserialization and then went on to regret it? I can't think of any, and don't agree with your conclusion. It works great, and manually writing serialization and matching deserialization code is terrible, annoying, error-prone work.
	▲	SuperV1234 an hour ago \| parent \| prev [-]
		I think this is a very bad take -- once you write it by hand you have to manually keep it in sync with the actual struct and ensure you made no mistakes. Reflection guarantees 1-1 future-proof mapping with the actual C++ struct, avoids boilerplate, and ensures that the serialization logic is correct.