Is anyone still using the CTRE library in 2026?

Back in 2019 an engineer/committee member made a splash by introducing CTRE, Compile Time Regular Expressions.

It was implemented using type aliases instead of constexpr function calls meaning it was easy to implement in C++11. Very impressive stuff.

It also gave you a nicer callsite spelling in C++20 leveraging generalized non-type template parameter passing.

I'm curious if anyone is still using it. If no, why not? I'd love to hear!

https://redd.it/1t05xxt
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Safe Optimistic Lock Coupling
https://databasearchitects.blogspot.com/2026/04/safe-optimistic-lock-coupling.html

https://redd.it/1t06gif
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I made a super fast CNN library for C++20 from scratch.

I was exploring Convolutional Neural Networks (CNNs) in more depth and I had an interesting idea of making a dependency free, header only cnn library for C++20.

I did some research and found out about tiny-dnn which is a cnn library for c++14, super fast but the developers stopped updating it back in 2016, so I decided to take on a challenge to make my own CNN library from scratch for c+ +20 with extreme performance tuning for CPU, and I did achieve close to what I was expecting.

I benchmarked with "pytorch" and the results were good enough to post, I have documented about the library here along with the benchmark results. At some instances it outperformed pytorch and I was shocked too.

Documentation- "https://Inkd.in/gNFF74JJ"

To get a rough idea on how fast is my engine it goes 97.51% accuracy on mnist dataset in just 25 seconds of training with a throughput of 2k+ images / second.

processor - Ryzen 7 5800H mobile

For overview -

My engine uses DAG layout

It has Zero Allocation

Multithreading Support

L1/L2 Cache Optimization

and a lot of internal stuffs going on, here is the repository link-

"https://github.com/KunwarPrabhat/CustomCNN"

My engine is still in its early stage so there are alot of things that can be fixed I need more devlopers to contribute if they're interested in it :))





https://redd.it/1t080e4
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Syntactic sugar of member function binding?

Instead of

std::bind_front(&Very::Long::Namespace::VeryLongClassName::method, pobject)

I'm currently using

#define BIND_FRONT(method, pobject) std::bind_front(&std::remove_cvref_t<decltype(*(pobject))>::method, (pobject))

BIND_FRONT(method, pobject)

I wonder if we can make

(pobject->method)

or

((*pobject).method)

or

((*pobject)::method)

a syntactic sugar of

BIND_FRONT(method, pobject) // a.k.a `std::bind_front(&std::remove_cvref_t<decltype(*(pobject))>::method, (pobject))`

Possible? Any drawbacks?

https://redd.it/1t0gryo
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Sub-microsecond timing on EC2 is way messier than I expected

Been doing sub-microsecond profiling on EC2 and kept getting wildly inconsistent cycle counts.

One mistake was using cpuid as the serialization barrier before rdtsc. On a VM that can be a mess, since cpuid often traps so the hypervisor can fake feature flags. So now the "measurement overhead" includes a VM exit, which is thousands of cycles on some runs.

Switching to lfence + rdtsc made the numbers a lot more stable.

Then I hit the calibration problem. Measuring TSC frequency with a short sleep() looked simple, but the results were all over the place. Scheduler delay, timer granularity, and probably vCPU steal time were enough to make the calibration useless at this scale. A busy-wait loop with pause gave me a much saner number.

Also forgot to pin the thread at first. rdtscp at least tells you when you migrated, but those samples are basically trash. Same with the first few iterations before icache/branch predictor warm up.

Curious what people here actually use for sub-microsecond timing. Do you just trust nanobench / Google Benchmark, or do you still end up writing your own rdtsc wrappers once VMs get involved?

https://redd.it/1t0o16n
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Juan Alday of Citadel Securities: Why C++ Wins in Finance (April 28th, 2026)
https://www.youtube.com/watch?v=InLxLEqg_fs

https://redd.it/1t0tnv4
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CSC4700: Parallel C++ for Scientific Applications
https://www.youtube.com/playlist?list=PL7vEgTL3Falab59uJoOb7AtFQKVuL0MV-

https://redd.it/1t0viu1
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External Polymorphism in C++26

While developing our Type Erasure library Any++ for C++23, we had to resort to a preprocessor-based EDSL to eliminate the boilerplate.

By studying the "C++26 Reflection Proposals," I was constantly searching for a way to replace this preprocessor programming.

Implementing Type Erasure requires three components:

- A "V-Table" for indirecting function calls.

- A "Facade" for the ergonomic connection between the data and the "V-Table."

- An "Adapter" to connect the functions of the "V-Table" to the specific type.

It suffices to describe one of these components. The other two can then be generated automatically.

One way to do this with C++26 is to specify in code the default adapter and generate the V-table and facade.

C++26 allows you to generate a class using define_aggregate.

The key is that the class can only contain data members.

However, since a data member can have an operator(), member functions can also be simulated this way.

These data members can be specified so that they don't occupy any memory. This allows you to access the enclosing class in the operator() and use the information it manages (the V-table and the data reference).

Interestingly, this method also enables static dispatch with an elegant interface.

To coincide with the GCC16 release and its excellent reflection implementation, I've sketched out such an API:

template <typename Self>
struct stringable{
    [[=default_{}]] // that says: when not specialized, call self.as_string() 
    static std::string as_string(Self const& self);
};

void print(std::vector<dyn<stringable>> const& things){
    for(auto& thing : things){
        std::println("{}", thing.as_string());
    }
}

template <>
struct stringable<int>{
    static std::string as_string(int const& self) {
        return std::to_string(self);
    }
};

template <>
struct stringable<std::string>{
    static std::string as_string(std::string const& self) {
        return self;
    }
};

struct foo{ double f; };
template <>
struct stringable<foo>{
    static std::string as_string(foo const& self){
        return "foo: " + std::to_string(self.f);
    }
};

struct boo { 
    bool b = false; 
    std::string as_string(){
        return std::string{"boo? "} + (b ? "T" : "F"); 
    }
};


int main(int argc, char *argv[]) {

    // static dispatch
    auto a1 = trait_as<int, stringable>{{42}};
    auto z_from_self = a1.as_string();
    std::println("z_from_trait = {}", z_from_self);

    // dynamic dispatch, reference semantics only
    int i = 4711;
    auto dyn_stringable = dyn<stringable>{i};
    auto z_from_dyn_stringable = dyn_stringable.as_string();
    std::println("z_from_dyn_stringable = {}", z_from_dyn_stringable);

    std::string s = "hello world";
    foo a_foo{3.14};
    boo a_boo{true};
    print({dyn<stringable>{i}, dyn<stringable>{s}, dyn<stringable>{a_foo}, dyn<stringable>{a_boo}});
}

Compiler Explorer

This is, of course, just a rough outline. The real value of a type erasure library lies in providing additional runtime capabilities (downcast, crosscast), lifetime mechanisms (shared, unique, value, etc.), and constant correctness.

Any++ provides all of this. As soon as Clang and MSVC also offer reflection, I will implement the presentated technique there.

For now, I have to thank the wizards who created this technical marvel: "C++ compile-time reflection"!

https://redd.it/1t14dw4
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Microsoft ODBC Driver 17.11.1 for SQL Server released

ODBC Driver 17.11.1 is out.

Fixes:

Parameter array processing: SQL\_ATTR\_PARAMS\_PROCESSED\_PTR now reports correctly, row counting fixed when SQL\_PARAM\_IGNORE is used
Connection error with Data Classification metadata in async mode
XA recovery transaction ID computation
RPM side-by-side installs now work
Debian package license acceptance

New platforms:

macOS 14, 15, 26
Debian 13
RHEL 10
Oracle Linux 9, 10
SUSE 16
Ubuntu 24.04, 25.10
Alpine 3.21, 3.22, 3.23

Download: https://learn.microsoft.com/en-us/sql/connect/odbc/download-odbc-driver-for-sql-server

Full blog post: Microsoft ODBC Driver 17.11.1 for SQL Server Released | Microsoft Community Hub

https://redd.it/1t15ffy
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stackless coroutines for gamedev in ~200 lines of C++
https://vittorioromeo.com/index/blog/sfex_coroutine.html

https://redd.it/1t171z7
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The STL for Geometry: Thirty-Year Evolution of C++ Libraries
https://polydera.com/algorithms/the-stl-for-geometry

https://redd.it/1t19d0y
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Variadic Visitation
https://breese.github.io/2026/05/01/variadic-visitation.html

https://redd.it/1t1gfcd
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Showcase/Request for Feedback Achieving 0.31ns Pathfinding on M1 for Search & Rescue Drones – Seeking advice on further optimization.]

Hi everyone,

I’m a student and student pilot from Vietnam, currently obsessed with combining Physics and C++ to solve real-world problems. My current project, H.A.L.O. Aegis, is a 600-700KB core designed for search-and-rescue drones operating in catastrophic environments (like collapsed buildings).

My goal was to create a "zero-latency" escape route identifier that can fit into the tiny L2 cache of embedded systems.

Current Specs:

Performance: \~0.326 ns per op on Apple M1 (measured via Google Benchmark).
Throughput: 3.0679G/s.
Memory Safety: Verified with AddressSanitizer (ASan).

The "Elephant in the room": Since I wanted to move fast on the rescue logic, I used AI to help generate some of the boilerplate and the bilingual interface (about 30-40% of the code). I manually hand-tuned the core physics-based logic to hit the sub-nanosecond mark.

Why I'm here: I’m planning to share this with NGOs like the Red Cross, but before I do, I want to make sure the code is truly "bulletproof."

Is my benchmarking methodology sound?
Are there any C++20 features I missed that could make this even more efficient for ARM64?
Please be kind—I'm still learning and I'm aware some of my internal comments might be messy (working on English-izing them!).

I'm ready for the "code review of a lifetime." If there’s anything not quite right, please let me know so I can fix it before it actually goes into a drone to save lives.

Project Link: https://github.com/Nguyenidkskibidi/halo-aegis-core

Thank you for your time and expertise!

https://redd.it/1t1h0do
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Read-Copy Update (RCU) API in C++26
https://people.kernel.org/paulmck/stupid-rcu-tricks-rcu-api-in-cpp26

https://redd.it/1t1gqwp
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Mathieu Ropert: The Performance Mindset
https://youtu.be/o-C6puc7nOk

https://redd.it/1t1k7k2
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CppCon 2025: Can Standard C++ Replace CUDA for GPU Acceleration? - Elmar Westphal
https://www.youtube.com/watch?v=EOvukoCyW7A

https://redd.it/1t1kopc
@r_cpp

Does anyone maintain an impl of the Chandler Carruth map API?

Lightning Talk (C++Now 2019, 8min): https://youtube.com/watch?v=kye4aD-KvTU

In 2019, Chandler presented the above talk describing a C++ map API. It's not compatible with the standard map types, but for greenfield projects I think it's an excellent choice.

I've considered implementing it myself, but hash tables are very subtle and finicky. I'd rather rely on a robust implementation.

Abseil has some excellent hash tables, but to my knowledge they do not support the small size/small buffer optimization. Chandler's hypothetical API does. Would be great to have the SIMD probing algorithm from Abseil implemented for an SSO map type.

https://redd.it/1t21nhu
@r_cpp

Post examples of using reflections in your projects

What the title says. I just want to see what interesting things people are using reflection for now that its in gcc. Thanks.

https://redd.it/1t25byx
@r_cpp

oo-alloc: i made a comprehensive learning resource for allocators in C++

hi!
i made a memory allocation library/learning resource. i wanted to learn more about them and i couldn't find one comprehensive source of knowledge, so i decided that i'll make one of my own:\].
it currently has these basic allocator types: arena (linear), stack, pool, free list, free tree, tracking, buddy, slab.
i gave my best to describe everything clearly in the readme, also added svg diagrams (written in Typst, btw). i plan to implement a bucket/size-segregated free list allocator as well.
hoping anyone will find this resource useful!
https://github.com/nihiL7331/oo-alloc

https://redd.it/1t287xq
@r_cpp

I made C++ coding problems where you build things like a mini Redis or a tiny interpreter — looking for feedback

I’ve been building a small platform with coding problems that are more “systems-style” rather than typical algorithm exercises.

The idea is to practice by building simplified versions of real components, but still in a problem format (input/output + tests).

Some examples:

* implement a Redis-like server (TCP + protocol parsing)
* build a tiny interpreter
* create a virtual filesystem
* write an expression evaluator

The problems are:

* runnable directly in the browser (no setup)
* open-ended (you decide design/architecture)
* supporting multi-file submissions

I’m trying to keep them doable in a few hours, not huge multi-day projects.

I’m curious what people here think:

* does this kind of problem feel useful for improving practical C++ skills?
* or would you prefer something more guided / closer to full projects?

Still early, so any feedback would be really helpful.

Link: [https://elitecode.pro/](https://elitecode.pro/)

https://redd.it/1t2941b
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Modern C++ Programming
https://federico-busato.github.io/Modern-CPP-Programming/

https://redd.it/1t2a4jz
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