[gmueckl]

Can cereal handle user defined types without having to write custom serialization and deserialization functions for each? At first glance this seems to be the main difference.

[nly]

Cereal requires a bit more copy & paste template boilerplate (it's a customization point) but they're basically the same.

* libnop uses a macro called NOP_STRUCTURE to create its key-value pairs.

* Cereal has a macro called CEREAL_NVP.

* Boost.Fusion has BOOST_FUSION_ADAPT_ASSOC_STRUCT

* Boost.Hana has BOOST_HANA_ADAPT_STRUCT

* Boost.Serialization has BOOST_SERIALIZATION_NVP

...all these things work the same way to get reflection

[coreytabaka]

Yes! Hopefully C++20 or C++25-ish will provide better alternatives for compile-time reflection.

Don't forget that libnop also has NOP_EXTERNAL_STRUCTURE (and friends) to decouple the annotation from the structure definition. This is handy when you have a C ABI with C++ internal implementation. I don't recall seeing a similar facility in other libraries.

[nly]

Most of the above macros work this way. Boost fusions macro will let you specify arbitrary code for getting and setting attributes.