C++26: Compile-Time Reflection for Faster, More Powerful Code

Hi there 👋 Today I want to give you a small glimpse into the future of C++ and honestly, it’s pretty exciting. With static reflection in C++26, we can finally inspect our types and structs at compile time and do things that used to feel like magic in languages like Java or C#. But here’s the real twist: ⚡ No runtime reflection overhead ⚡ Everything happens at compile time ⚡ Zero runtime penalty Yes, compilation might take a little longer… but let’s be honest if you’re already using heavy templates, you’re probably used to that 😅 The power you get in return is incredible. As a small example, I wrote a tiny function that can print almost any struct automatically using our new friend std::meta. Of course, it’s a quick prototype and there are still edge cases I didn’t wrap in it but the idea is clear: 👉 We can inspect types 👉 Iterate over members at compile time 👉 Generate code based on structure And printing structs is just the beginning. If you watched my Python bindings talk at CppCon this year, you might already imagine where this is going… Reflection + C++ bindings = extremely powerful tooling. Think about: automatic bindings serialization schema generation logging / debugging tools meta-driven frameworks The number of possibilities here is huge. Personally, I can’t wait to start using this in production. C++ keeps evolving, and features like this show that the language is still pushing forward in powerful ways. ⚙️ What would YOU build first with C++ static reflection? #cpp #cpp26 #programming #softwareengineering #reflection

  • code that shows a function to print structs with static reflections

if you were wondering about how the output looks:

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1) There are three main uses I can think of for this feature: a) Printing (you've already done). b) Deserializtaion (next logical step). c) Haskell style automatic traversal over all elements in a tree/DAG-like structure through its pointers. 2) I'd be surprised if many people would use this feature directly, it's likely this would be used by a small amount of library builders, and then lots of people will implement stuff on top of it.

But with God level readability 😉

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The biggest draw is that it all happens at compile time. Brilliant.

Do you agree the syntax is not so nice as it could be ?:)

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Victor Cruceru

Software Development Engineer - Linux/ UNIX/ C++/ C/ Python

1mo

From what I'm reading this feature is available in GCC 16 and it is labeled as experimental.

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Look at what they’ve done to mimic a fraction of the power of Zig! (Zig is basically _the_ language for compile time computation, with types and everything else)

Because the syntax is so terrible - I started writing a TS to C++ transpiler that lets me use TS to do all my type manipulation and use C++ for its performance. It uses TS inbuilt transformer API that can give you the AST and allow you to modify it or generate raw text. I was also able to implement partial application, pipelines and function composition , defer statement and so on with relatively clean syntax. Also haskell style lazy pipelines The syntax is a bit strained because $ is the only token in TS that can be used as a base for new syntax, but the code is still way better and TS own type meta programming is way more intuitive than C++

Uhhh. Thinking about stuff like this, reflecting implies unknown, dynamic situation. Like rubys method_missing. I feel like if you need to do this in compile time and classical plain constructs are not sufficient, you are probably doing something strange.

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