#annotations
3 posts tagged #annotations.
Annotations: tag-driven serialization comes to C++
P3394 brings serde-style and Jackson-style attribute programming to C++: rename, skip, skip_if_empty, rename_all — all as plain user-defined values queryable by reflection.
Define your own function colors: compile-time caller checks with C++26 reflection
C++ already enforces function colors -- consteval, CUDA's __device__, Clang's [[clang::nonblocking]] -- but every one of them needed a compiler change. C++26's std::meta::current_function() (P3795R1) lets a callee reflect on its caller at compile time, so you can paint your own colors as a 20-line library: audio-thread safety, capability tokens, or architectural layers that refuse to compile when called from the wrong place. Here is the pattern, three professional uses, and exactly where it breaks.
Reflection + annotations for hashing: opt out of fields, not whole structs
Krystian Piekos's May 29 post on infotraining.pl shows the cleanest demo so far of P3394 annotations combined with P2996 reflection: opt structs into hashing with [[=hashable]], and opt individual fields out with [[=skipped_for_hash]]. The Hashable concept and the calculate_hash walker fit in 40 lines. No macros.