Msgpack23 – A modern, header-only C++ library for MessagePack (de)serialization | Hacker News Reader

Msgpack23 – A modern, header-only C++ library for MessagePack (de)serialization

github.com

29 pointsgjvc17 comments

Does C(++) still not have a broadly used package manager? If not, that's mind blowing.

The header only fad seems to because of a lack of one? IIRC they're more costly compilation wise too.

The STL was originally header-only. Not sure if it still is.

Conan and vcpkg are the two big ones, and there are several smaller ones. Since they picked up in popularity about a decade ago, it's become increasingly unusual for "header only" to be a selling point for a library (though of course some naturally are if they're fully templated).

I also wonder why "header only" is advertized.

As for the compilation cost, modern C++ tries to adress that with modules.

If a third-party dep has a build process any more complicated than dropping the cpp files into your own project, integrating with their build system is going to suck. (No two C++ projects use the same build system)

Thx for the explanation, makes sense.

There isn't as big of a boost as you'd think, since for a templated function you have to #include the entire definition of said function in whatever source file is using it.

Yup, which is why a project that is serious about compilation time splits off type-independent parts into .cpp files that can be compiled separately, improving the speed of compilation for users of that template.

I consider being a header-only "library" a code smell. It's purely for convenience, at the cost of compilation speed.

It does, vcpkg and conan, but some folks refuse to learn how to use compiled languages and treat C and C++ as if they were Python or JavaScript.

Every project handles this differently, and because of the huge variety of environments and potential build complications in comparison to pretty much every other language, I think it would be very hard to get a supermajority of the C and C++ communities in agreement on a package manager.

That being said, there are package managers like vcpkg and conan that work just fine. They will just never be ubiquitous like pip or npm or cargo. Projects are going to continue to want to manage these sorts of issues themselves in a lot of circumstances.

For new projects on a supported platform, I'd recommend going ahead and just using vcpkg. But that's just my opinion. And there is code I work on where that wouldn't be possible. Plus some people just don't like the things that package managers tend to encourage.

>The header only fad seems to because of a lack of one? IIRC they're more costly compilation wise too.

Templates cannot be compiled. They have to necesserily be distributed as header files. Furthermore, header files, unlike compiled code are easier to support on a wider variaty of platforms.

They are more constly to include, as you said.

You could technically create concrete classes or functions from the templates by supplying all the necessary type arguments, and compile that. But then the developer using your library will only be able to "use the template" with those particular type arguments. The flexibility that the templates offer is removed.

I recently discovered the usefulness of msgpack with a fixed scheme. Wrote a library for encoding/decoding msgpack based on structs. Like protobuf, it's compact and possible to evolve, plus I actually find it easier to deal with, since it decodes to native types, not protobuf wrappers. And you can read it in basically any language, which makes is super easy to debugging binary files/streams.

nlohmann::json also does msgpack and is header-only, and it's the most popular JSON lib for C++ https://github.com/nlohmann/json?tab=readme-ov-file#design-g...

At this point, what is the difference between MessagePack and CBOR?

Not sure but I decided on CBOR for my own project because I found a nice open source C library called TinyCBOR which can serialize and deserialize without any memory allocations. It works using an iterator that you manually move up and down into sub containers.

https://intel.github.io/tinycbor/current/

CBOR seems a bit more complicated. I've written a few msgpack encoders/decoders, usually over a weekend using https://github.com/msgpack/msgpack/blob/master/spec.md

See https://github.com/PeerDB-io/gluamsgpack

I found this: https://news.ycombinator.com/item?id=42664664

Unfortunate.

Reply on news.ycombinator.com