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P4043R0: Are C++ Contracts Ready to Ship in C++26?
Are you watching the ISO C++ standardization pipeline? Looking for the latest status about C++ Contracts?
I'm curious to see the non-WG21 C++ community opinion.
The C++26 Contracts facility (P2900) is currently in the Working Draft, but the design is still the subject of substantial discussion inside the committee.
This paper raises the question of whether Contracts are ready to ship in C++26 or whether the feature should be deferred to a later standard.
Click -> P4043R0: Are C++ Contracts Ready to Ship in C++26?
I'm curious to hear the perspective of the broader C++ community outside WG21:
\- Do you expect to use Contracts?
\- Does the current design make sense to you?
\- Would you prefer a simpler model?
Feedback welcome.
https://redd.it/1rnh401
@r_cpp
I made a single-header, non-intrusive IoC Container in C++17
[https://github.com/SirusDoma/Genode.IoC](https://github.com/SirusDoma/Genode.IoC)
A non-intrusive, single-header IoC container for C++17.
I was inspired after stumbling across a compiler loophole I found [here](https://alexpolt.github.io/type-loophole.html). Just now, I rewrote the whole thing without relying on that loophole because I just found out that my game sometimes won't compile on clang macOS without some workarounds.
Anyway, this is a similar concept to Java Spring, or C# Generic Host / Autofac, but unlike [kangaru](https://github.com/gracicot/kangaru) or other IoC libraries, this one is single header-only and most importantly: **non-intrusive**. Meaning you don't have to add anything extra to your classes, and it just works.
I have used this previously to develop a [serious game](https://www.reddit.com/r/gamedev/comments/1rldvqa/i_remade_an_online_retro_game_by_reverse/) with complex dependency trees (although it uses a previous version of this library, please check that link, it's made with C++ too), and a game work-in-progress that I'm currently working on with the new version I just pushed.
Template programming is arcane magic to me, so if you found something flawed / can be improved, please let me know and go easy on me 😅
**EDIT**
As requested, let me briefly talk about what IoC is:
IoC container stands for [Inversion of Control](https://en.wikipedia.org/wiki/Inversion_of_control), as mentioned, a similar concept to [Spring in Java](https://docs.spring.io/spring-framework/reference/core/beans/introduction.html). By extension, it is a [dependency injection](https://en.wikipedia.org/wiki/Dependency_injection) pattern that manages and abstracts dependencies in your code.
Imagine you have the following classes in your app:
struct NetworkSystem
{
NetworkSystem(Config& c, Logger& l, Timer& t, Profiler* p)
: config(&c), logger(&l), timer(&t), profiler(&p) {}
Config* config; Logger* logger; Timer* timer; Profiler *profiler;
};
In a plain old-school way, you initialize the `NetworkSystem` by doing this:
auto config = Config(fileName);
auto logger = StdOutLogger();
auto timer = Timer();
auto profiler = RealProfiler(someInternalEngine, someDependency, etc);
auto networkSystem = NetworkSystem(config, logger, timer, profiler);
And you have to manage the lifetime of these components individually. With IoC, you could do something like this:
auto ioc = Gx::Context(); // using my lib as example
// Using custom init
// All classes that require config in their constructor will be using this config instance as long as they are created via this "ioc" object.
ioc.Provide<Config>([] (auto& ctx) {
return std::make_unique<Config>(fileName);
});
// Usually you have to tell container which concrete class to use if the constructor parameter relies on abstract class
// For example, Logger is an abstract class and you want to use StdOut
ioc.Provide<Logger, StdOutLogger>();
// Now simply call this to create network system
networkSystem = ioc.Require<NetworkSystem>(); // will create NetworkSystem, all dependencies created automatically inside the container, and it will use StdOutLogger
That's the gist of it. Most of the IoC container implementations are customizable, meaning you can control the construction of your class object if needed and automate the rest.
Also, the lifetime of the objects is tied to the IoC container; this means if the container is destroyed, all objects are destroyed (typically with some exceptions; in my lib, using `Instantiate<T>` returns a `std::unique_ptr<T>`). On top of that, depending on the implementation, some libraries provide sophisticated ways to manage the lifetime.
I would suggest familiarizing yourself with the IoC pattern before trying it out to avoid anti-patterns: For example, passing the container itself to the constructor is considered an anti-pattern. The following code
Exploring Mutable Consteval State in C++26
https://friedkeenan.github.io/posts/exploring-mutable-consteval-state/
https://redd.it/1ro1gfz
@r_cpp
Announcing TEC v1.0.0: Lightweight Header-Only Template-Based C++ Library
Hey r/cpp!
I'm excited to announce the first stable release of TEC, a lightweight, header-only, template-based C++ library for multithreaded execution in concurrent environments. This version marks the foundation of TEC, providing core functionalities for a wide range of applications, from embedded systems to distributed networking.
TEC is Apache 2.0-licensed, open-source, and ready for contributions. Check out the GitHub repo for the full README, examples, and API docs.
## Key Features
- Header-Only Design: Seamless integration with no compilation dependencies, enabling rapid prototyping and cross-platform deployment.
- No external dependencies: TEC can be dropped into any project without requiring third-party libraries or tools (the use of gRPC and Zlib is optional).
- Networking Capabilities: Efficient BSD socked based servers and clients with low memory footprint, ideal for communication in distributed systems.
- gRPC Ecosystem: (optional) The TEC library streamlines the development of gRPC servers and clients by leveraging the universal TEC's Daemon API (DAPI).
- Distributed Systems Modeling: Low-overhead tools for simulating large-scale architectures, handling high connection volumes in cloud or edge environments.
## Getting Started
To use TEC, simply include the header files in your C++ project. No additional builds required. Check the README for detailed usage examples and API documentation.
## Known Issues
- None reported at this time. Please open an issue if you encounter any problems.
## Feedback and Contributions
This is our first release, so we'd love your thoughts! Star the repo, open issues for bugs/features, or submit PRs via our CONTRIBUTING.
Thanks for checking it out.
Cheers,
The Emacs Cat
(Developer of TEC)
https://redd.it/1rhv2ld
@r_cpp
Should C++ Give More Priority to Syntax Quality?
I’ve been thinking about this for a while and I’m curious what others here think.
The C++ committee does an incredible job focusing on zero overhead abstractions and performance. But I sometimes feel that syntax quality and aesthetic consistency don’t get the same level of attention.
Recently I’ve noticed more features being proposed or added with syntax that feels… awkward or visually noisy. A few examples:
* `co_await`
* The reflection operator `^^`
* The proposed `e.try?` try operator
And many other similar things. Individually none of these are catastrophic. But collectively, I worry about the long-term impact. C++ is already a dense and complex language. If new features keep introducing unusual tokens or visually jarring constructs there is a risks of becoming harder to reason about at a glance.
Should syntax design be given equal weight alongside performance?
I’d love to hear perspectives from people who follow WG21 discussions more closely. Is this something that’s actively debated? Or is syntax mostly a secondary concern compared to semantics and performance?
Curious to hear what others think.
https://redd.it/1rhrg10
@r_cpp
Language specific package managers are a horrible idea
Package managers should only deal with package cache and have a scripting interface.
Package managers trying to act smart only makes our jobs harder as evidenced by looking at the issue pages of global package registries.
I recommend everyone here to switch to Conan and not use any abstractions for the build systems, disable remote and use a deployment script or using full deploy as an option. It is not ideal, but it doesn't stand in your way.
https://redd.it/1rh97ru
@r_cpp
Data structures and algorithms
I'm new to programming and I started learning cpp as a first language, and I'm currently struggling to understand Data structures (sorting algorithms and search algorithms are kidna understandable but I didn't fully consumed it , but stacks are just straight outta hell ) and I feel lost , I don't seem to have a big problem with object oriented programming and file management so I'm I just stupid or DS is just this hard? , and is there any good coursess or YouTube videos that explains it good? And also a good oop explanation videos would help, thanks 😊 🙏
https://redd.it/1rhe1t0
@r_cpp
Mocking the Standard Template Library
https://middleraster.github.io/TBCI/MockingTheSTL.html
https://redd.it/1rgskhw
@r_cpp
Upscaled files detector
I built a small C++20 tool that detects MP3-to-WAV/FLAC upscaling using spectral analysis, and wanted to share it here since the core is pretty DSP-heavy.
The detection works by running a Cooley-Tukey FFT over multiple frames of the file (with Hann windowing to reduce leakage), then comparing the energy ratio between the 10–16 kHz mid band and everything above 16 kHz. MP3 encoders tend to hard-cut the upper frequencies, so a consistently low high/mid ratio across >70% of valid frames flags the file as probably transcoded. Frames below an RMS threshold are skipped to avoid silent passages skewing the result.
The FFT itself has an AVX2-optimized butterfly stage — I wanted to experiment with SIMD intrinsics, so when four or more butterflies remain in a block it processes them in parallel using 256-bit registers (4 complex numbers at a time via moveldup/movehdup + addsub_ps). The IFFT reuses the forward pass via the conjugate symmetry trick rather than a separate implementation.
There's also a real-time spectrogram and stereo volume meter rendered in the terminal with FTXUI, and a microphone passthrough mode with basic frequency-domain feedback suppression.
The detection heuristic is pretty empirical and I know it has limitations — it doesn't account for formats like AAC which have different cutoff characteristics, and the fixed 16 kHz threshold doesn't adapt to the file's sample rate ceiling. I'd be curious whether anyone here has thoughts on more robust approaches (spectral flatness, entropy measures, etc.).
Repo: https://github.com/giorgiogamba/avil
https://redd.it/1rh42mr
@r_cpp
Am I the only one who feels like header files in C/C++ are duplication?
We declare things in headers, define them in source, keep them in sync manually, sprinkle include guards everywhere... all to prevent problems caused by the very system we are forced to use. It's like writing code to defend against the language's file model rather than solving actual problems.
And include guards especially - why is "dont include the same header twice" something every project has to re-implement manually? Why isn't that just the compiler's default behavior? Who is intentionally including the same header multiple times and thinking "yes, this is good design"?
It feels like a historical artifact that never got replaced. Other languages let the compiler understand structure directly, but here we maintain parallel representations of the same interface.
Why can't modern C++ just:
treat headers as implicitly guarded, and maybe
auto-generate interface declarations from source files?
https://redd.it/1rgyeqp
@r_cpp
Serialization by contract and IPC
https://github.com/amarmer/SerializationByContract
https://redd.it/1rb2yes
@r_cpp
Apache Fory C++: Fast Serialization with Shared/Circular Reference Tracking, Polymorphism, Schema Evolutionn and up to 12x Faster Than Protobuf
We just released Apache Fory Serialization support for c++:
https://fory.apache.org/blog/fory\_cpp\_blazing\_fast\_serialization\_framework
Highlights:
1. Automatic idiomatic cross-language serializaton: no adapter layer, serialize in C++, deserialize in Python.
2. Polymorphism via smart pointers: Fory detects std::is_polymorphic<T> automatically. Serialize through a shared_ptr<Animal>, get a Dog back.
3. Circular/shared reference tracking: Shared objects are serialized once and encoded as back-references. Cycles don't overflow the stack.
4. Schema evolution: Compatible mode matches fields by name/id, not position. Add fields on one side without coordinating deployments.
5. IDL compiler (optional): foryc ecommerce.fdl --cpp_out ./gen generates idiomatic code for every language from one schema. Generated code can be used as domain objects directly
6. 6. Row format: O(1) random field access by index, useful for analytics workloads where you only read a few fields per record.
Throughput vs. Protobuf: up to 12x depending on workload.
GitHub: https://github.com/apache/fory
C++ docs: https://fory.apache.org/docs/guide/cpp
I’d really like critical feedback on API ergonomics, and production fit.
https://redd.it/1r8a0zt
@r_cpp
Learn C++ by Example • Frances Buontempo & Matt Godbolt
https://youtu.be/PXKICIiXEUM?list=PLEx5khR4g7PJbSLmADahf0LOpTLifiCra
https://redd.it/1r8yslh
@r_cpp
Problems with a weak tryLock operation in C and C++ standards
https://forums.swift.org/t/se-0512-document-that-mutex-withlockifavailable-cannot-spuriously-fail/84789/3
https://redd.it/1r94jgk
@r_cpp
BitFields API: Type-Safe Bit Packing for Lock-Free Data Structures
https://rocksdb.org/blog/2025/12/31/bit-fields-api.html
https://redd.it/1ra6tux
@r_cpp
illustrates the anti-pattern:
struct NetworkSystem
{
NetworkSystem(Gx::Context& ioc) // DON'T DO THIS. Stick with the example I provided above
{
config = ioc.Require<Config>();
logger = ioc.Require<Logger>();
timer = ioc.Require<Timer>();
profiler = ioc.Require<Profiler>();
}
Config* config; Logger* logger; Timer* timer; Profiler *profiler;
};
auto ioc = Gx::Context();
auto networkSystem = NetworkSystem(ioc); // just don't
The above case is an anti-pattern because **it hides dependencies.** When a class receives the entire container, its constructor signature no longer tells you what it actually needs, which defeats the purpose of [DI](https://en.wikipedia.org/wiki/Dependency_injection). IoC container should be primarily used in the root composition of your classes' initialization (e.g, your `main()`).
In addition, many IoC containers perform compile-time checks to some extent regardless of the language. By passing the container directly, you are giving up compile-time checks that the library can otherwise perform (e.g., `ioc.Require<NetworkSystem>()` may fail at compile-time if one of the dependencies is not constructible either by the library (multiple ambiguous constructors) or by the nature of the class itself). I think we all could agree that we should enforce compile-time checks whenever possible.
Just like other programming patterns, some exceptions may apply, and it might be more practical to go with anti-pattern in some particular situations (that's why `Require<T>` in my lib is exposed anyway, it could be used for different purposes).
There might be other anti-patterns I couldn't remember off the top of my head, but the above is the most common mistake. There are a bunch of resources online that discuss this.
This is a pretty common concept for web dev folk (and maybe gamedev?), but I guess it is not for your typical C++ dev
https://redd.it/1ro288e
@r_cpp
peel - C++ bindings generator for GObject-based libraries
https://gitlab.gnome.org/bugaevc/peel
https://redd.it/1rod1sn
@r_cpp
C++ Show and Tell - March 2026
Use this thread to share anything you've written in C++. This includes:
* a tool you've written
* a game you've been working on
* your first non-trivial C++ program
The rules of this thread are very straight forward:
* The project must involve C++ in some way.
* It must be something you (alone or with others) have done.
* Please share a link, if applicable.
* Please post images, if applicable.
If you're working on a C++ library, you can also share new releases or major updates in a dedicated post as before. The line we're drawing is between "written in C++" and "useful for C++ programmers specifically". If you're writing a C++ library or tool for C++ developers, that's something C++ programmers can use and is on-topic for a main submission. It's different if you're just using C++ to implement a generic program that isn't specifically about C++: you're free to share it here, but it wouldn't quite fit as a standalone post.
Last month's thread: https://www.reddit.com/r/cpp/comments/1qvkkfn/c_show_and_tell_february_2026/
https://redd.it/1ri7ept
@r_cpp
Always actual list of the latest C++ related YT videos
https://www.swedencpp.se/videos
https://redd.it/1rhtj5w
@r_cpp
Good, basic* game networking library?
I want to get a simple server-client system up for a multiplayer game, and I've been poking around to find some simple networking implementations but haven't found many. I've used enet itself before but I would like something a little more friendly in terms of usability? I know it's good but something about it is not terribly enjoyable to use for games.
https://redd.it/1rggeut
@r_cpp
[OpenGL C++] 3D Voxel Engine Tutorial
https://youtube.com/playlist?list=PLQ7CpbxNS-_YP1WhUAVmxRQuF_a4PLju_&si=Hq5Jjp2OAv5heZbL
https://redd.it/1rgm7ae
@r_cpp
What makes a game tick? Part 9 - Data Driven Multi-Threading Scheduler · Mathieu Ropert
https://mropert.github.io/2026/02/27/making_games_tick_part9/
https://redd.it/1rgeve1
@r_cpp
Power of C++26 Reflection: Strong (opaque) type definitions
Inspired by a similar [previous thread](https://www.reddit.com/r/cpp/comments/1mwv927/the_power_of_c26_reflection_first_class/) showcasing cool uses for C++26 reflection.
With reflection, you can easily create "opaque" type definitions, i.e "strong types". It works by having an inner value stored, and wrapping over all public member functions.
Note: I am using `queue_injection { ... }` with the EDG experimental reflection, which afaik wasn't actually integrated into the C++26 standard, but without it you would simply need two build stages for codegen. This is also just a proof of concept, some features aren't fully developed (e.g aggregate initialization)
[godbolt](https://godbolt.org/z/8n4r5Ydvz)
struct Item { /* ... */ }; // name, price as methods
struct FoodItem;
struct BookItem;
struct MovieItem;
consteval {
make_strong_typedef(^^FoodItem, ^^Item);
make_strong_typedef(^^BookItem, ^^Item);
make_strong_typedef(^^MovieItem, ^^Item);
}
// Fully distinct types
void display(FoodItem &i) {
std::cout << "Food: " << i.name() << ", " << i.price() << std::endl;
}
void display(BookItem &i) {
std::cout << "Book: " << i.name() << ", " << i.price() << std::endl;
}
int main() {
FoodItem fi("apple", 10); // works if Item constructor isn't marked explicit
FoodItem fi_conversion(Item{"chocolate", 5}); // otherwise
BookItem bi("the art of war", 20);
MovieItem mi("interstellar", 25);
display(fi);
display(bi);
// display(Item{"hello", 1}); // incorrect, missing display(Item&) function
// display(mi); // incorrect, missing display(MovieItem&) function
}
https://redd.it/1rgo4s9
@r_cpp
Real-time Safety — Guaranteed by the Compiler! - Anders Schau Knatten Meeting C++ 2025
https://www.youtube.com/watch?v=4aALnxHt9bU
https://redd.it/1rh0v7u
@r_cpp
C++26 Reflection + PyBind11 for algo trading
https://github.com/profitviews/merton-market-maker
https://redd.it/1rbjsxk
@r_cpp
Implementing your own asynchronous runtime for C++ coroutines
Hi all! Last time I wrote a blog post about writing your own C++ coroutines. Now, I wanted to highlight how to write your own C++ asynchronous runtime for your coroutines.
https://rhidian-server.com/how-to-create-your-own-asynchronous-runtime-in-c/
Thanks for reading, and let me know if you have any comments!
https://redd.it/1ratu13
@r_cpp
Experimental adaptive sort - matches std::sort on random input, 2-8x faster on structured data
Hi all,
I’ve been developing an adaptive sorting algorithm, tentatively called **JesseSort**, which aims to exploit partial order in input data while still being competitive with standard library sorts on random input. I’m looking for feedback on design and potential adoption strategies.
# What it does
* Detects natural runs in the input (ascending, descending, or random) with a tiny lookahead.
* Maintains two sets of piles for ascending and descending runs, essentially a dual-patience sort.
* Falls back to tiny 8-value bitonic sort networks on detected random regions.
* When this random-input block is run too many times, it falls back to **std::sort**.
* Currently merges adjacent runs in a naive/bottom-up way.
# Current numbers
Median runtime ratios vs `std::sort` over 100 trials:
|Input Type|1k Values|10k|100k|1M|
|:-|:-|:-|:-|:-|
|Random|**0.984**|1.032|1.042|1.088|
|Sorted|1.022|**0.679**|**0.583**|1.448?|
|Reverse|1.636|1.076|**0.900**|2.101?|
|Sorted+Noise(5%)|1.048|1.041|1.079|1.201|
|Random+Repeats(50%)|1.037|1.032|1.031|1.089|
|Jitter|1.012|**0.674**|**0.586**|1.443?|
|Alternating|**0.829**|1.011|**0.974**|1.018|
|Sawtooth|1.121|**0.960**|**0.978**|1.072|
|BlockSorted|1.046|**0.950**|**0.928**|1.153|
|OrganPipe|**0.446**|**0.232**|**0.138**|**0.268**|
|Rotated|**0.596**|**0.522**|**0.396**|**0.716**|
|Signal|1.402|**0.828**|**0.659**|**0.582**|
**Notes:**
* Ratios are `JesseSort` / `std::sort`. **Values <1 indicate JesseSort is faster.** 0.5 means JesseSort takes half the time (2x faster). 2.0 means JesseSort takes twice as much time (2x slower).
* Large input blow-ups (`?`) appear to be outliers on my machine, but would be curious to see if others see the same pattern.
# Current issues / questions
1. **Handoff threshold:** Detecting random input too early loses semi-structured gains; too late slows random input. How should this balance be tuned?
2. **Fallback vs. std::sort:** Could JesseSort itself (dual patience games) serve as a better fallback than heap sort in standard introsort implementations?
3. **Merge optimizations:** Current merge is bottom-up adjacent. I’ve prototyped a TimSort-style merge that merges smaller runs first. Minor speedups in most cases but I haven't tested it enough.
4. **Memory layout & cache:** Some sensitivity to variable placement and data alignment is noticeable. Any advice for robust layout-sensitive optimizations?
5. **Real-world adoption:** Even if slightly slower on purely random input (\~5%), the structured input gains are often >50%. Would such an algorithm be worth promoting or considered niche? If the hit to random input is too significant, maybe this would find a better home as an alternative like `std::structured_sort`?
I’m looking for input on:
* Algorithmic improvements, especially for the random vs structured handoff
* Practical concerns for integration into standard libraries
* Benchmark methodology for mixed input distributions
* Real-world test datasets that might showcase advantages
Code and full details are available here: [https://github.com/lewj85/jessesort](https://github.com/lewj85/jessesort)
Thanks
https://redd.it/1r8n7vi
@r_cpp
MSVC Build Tools 14.51 Preview released
https://devblogs.microsoft.com/cppblog/microsoft-c-msvc-build-tools-v14-51-preview-released-how-to-opt-in/
https://redd.it/1r8ufqi
@r_cpp
Parallel C++ for Scientific Applications: Tasks & Concurrency (2nd Part)
https://www.youtube.com/watch?v=l-QUaAH_JJs
https://redd.it/1r9ulqk
@r_cpp
I made a minimal SDL3 starter template with CMake and vcpkg — cross-platform, no bundled libs
Been doing C++ game dev for a while and got tired of setting up the same boilerplate every time I started a new SDL project. Put together a clean starter template with SDL3, SDL3_image, and SDL3_ttf managed via vcpkg so dependencies just work on Linux, macOS, and Windows.
Includes a basic SDLWindow class, hardware-accelerated renderer, and a game loop ready to go. Nothing fancy, just a solid starting point.
https://github.com/Tanner-Davison/sdl3-starter-template
Happy to answer questions about the setup or take feedback on the structure.
https://redd.it/1rajyp5
@r_cpp