Meeting 25 May 2017

C++ feature polls by Bryce Lelbach

C++20 C++23 C++26 C++29 C++32 C++35 C++38 C++41 C++44 C++47 C++50

Concepts of the Upcoming Ranges TS - Eric Niebler [NWCPP]

  • What is in Ranges
  • What is in Ranges TS (Ranges minus the good stuff, like views or actions)
  • “Based on Concepts TS which was finalised, what, 2–3 years ago?” Hah!
  • Latest draft:
  • C++11 implementation:
  • Concepts-based implementation:
  • This is the beginning of STLv2 (namespace std2)
  • Eric shows snippers of code that use the standard library and then converts them to use ranges — so nice!
  • “Projection” is basically a map using a unary function
  • SentinelsHow to convert your own algorithms to using Ranges TS
  • Ranges and coroutines: — lets you write lazy ranges which work very well with views
  • Async ranges based on coroutines ⇒ reactive programming! Does Eric know about RxCpp?

History of Time: Asynchronous C++ - Steven Simpson [ACCU 2017]

  • how not to implement network server
  • don’t use one thread per connection
  • epoll (IO completion ports): OS tells us when a connection is ready, so we don’t need threads, don’t have race conditions, and can scale well
  • overview of callback libraries, including Boost ASIO
  • live reimplementation of ASIO event loop
  • “futures” in event loops: no threads, but syntactic sugar around callbacks: like JavaScript promise or Python deferred
  • coroutines (“user-space threads”)
  • fibers are the same as stackful coroutines
  • his “coroutine” code is using Boost coroutines, not Coroutines TS
  • demonstrates performance degradation and scaling capabilities of all the way of implementing async code
  • slide 116 has a summary table at 1:26:30 Summary

C++11 Multithreading done right? - Rainer Grimm @ Meeting C++ 2014

  • discusses snippets of code, best practices, what not to do
  • engages the audience (a bit too much IMHO) ⇒ lots of interruptions, sometimes they see his bugs and it all gets very confusing
  • poor volunteer with the microphone running around like mad trying his best to catch random replies across the huge room


  • C++ is efficient, close to metal, you can do anything, and tooling is readily available
  • Soft real-time constraints, speed is king
  • Memory constraints for embedded encoders/decoders
  • C++ toolchain permits optimisations that are simply not possible in other languages
  • SIMD

Using C++ Resumable Functions with Libuv

GitHub :: Blog post

  • “Libuv is a C library that provides the asynchronous I/O in Node.js. While it was explicitly designed for use by Node.js, it can be used on its own and provides a common cross-platform API, abstracting away the various platform-specific asynchronous APIs.”
  • “With resumable functions, you can write code that looks very sequential but executes asynchronously.”
  • Header-only wrappers for the main lib functions

Using C++ Coroutines with Boost C++ Libraries

Blog post

  • Using coroutines with boost::future and boost::asio
  • Interesting techniques for adapting future/promise and callback-based APIs to using coroutines
  • I expect more adaptations like this coming in the near future

await/yield: C++ coroutines - Zbigniew Skowron


  • Current status (as of 30 Nov 2016)
  • Overview and motivation
  • Stackful vs. stackless
  • Coroutines as generators
  • Coroutines instead of callbacks
  • Awaitable types vs. coroutine return types
  • Gotchas