ISO C++ is the official website for the C++ programming language standardization committee, providing information, resources, and updates on the evolution of the C++ language. With a focus on language features, library enhancements, and standardization efforts, ISO C++ keeps developers informed about the latest developments in C++ programming. Developers can learn about upcoming language features, review proposals for language changes, and contribute to the evolution of the C++ language through active participation in the standardization process.

C++26 is introducing compile-time reflection, and this post compares it with reflection capabilities in Python, Java, C#, and Rust using a concrete example: implementing a generic object_to_string function. Python uses runtime __dict__ lookups, Java and C# use runtime reflection APIs backed by their runtime environments, and Rust uses procedural macros (which are compile-time code generation but not true reflection). C++26 reflection uses the ^^ operator to enter reflection space, std::meta functions to traverse it, and splicers [:...:] to leave it — all evaluated at compile time, making it a zero-cost abstraction. The key distinction is that C++ reflection evaporates after constant evaluation, producing code equivalent to hand-written specializations, unlike Java/C# where reflection incurs runtime overhead. Rust's procedural macros are limited to token-level transformations without the ability to query type definitions, making them code generation rather than true reflection.

Flavours of Reflection — Semantics