That was fast!

Tim just added this comment on the GotW #3 Solution blog post from last year:

Are you sure you can use auto in lambda like this?
I can not compile the code and I’m pretty sure auto does not work here.

If you mean auto as a lambda parameter type, such as

[](auto& s){ use(s); }

then yes, it’s (now) legal): That’s a new feature in currently-being-finalized C++14 standard, and it’s called “generic lambdas.” It means that the compiler-generated closure object’s


is a template, so you can call the same closure object multiple times with different types and get the templated operator stamped out for each set of types it’s called with.

Major compilers are now adding support for this. As of this writing, all of GCC, Clang, and Visual C++ have implemented the basic feature and you can get it in CTP/preview/alpha releases of each, such as GCC or Clang trunk, or Visual C++ November 2013 CTP. I can’t remember offhand which of those compilers have shipped an official release since adding it (VC++ has not) but they’ll all have it in their next released versions.

By the way, isn’t it wonderful that, for the first time in the history of C++, multiple major compilers are in pretty good sync like this, both with each other and with the standard? I think that’s awesome.

If you’re at Build in San Francisco tomorrow afternoon, I invite you to swing by and spend an hour with us in session 2-661:

Modern C++: What you need to know

by Herb Sutter

Build 2014, Room 2005
2:30-3:30 pm, Thursday April 3, 2014

If you’re new to C++, this talk is aimed directly at you. I was asked to give a “foundational talk” about C++, and I decided that meant I should focus on addressing two questions that I get a lot these days:

  • FAQ #1 (1-2 slides): When should I use C++ compared to another language – on all platforms in general, and on Microsoft platforms in particular?
  • FAQ #2 (lots of slides): What should I know about C++ if I’m a {Java|C#|JavaScript|Python|…} developer?

Even if you’re a seasoned C++ developer, there are some nuggets and data points in the middle of the talk that I think you will find useful in your own work, and I hope that the talk as a whole will be helpful to you in providing a way to explain C++’s value proposition and give (or link to) an answer when someone asks you FAQ #2.

I think it will be recorded, and will post a link here when the recording is available.

I look forward to seeing many of you there tomorrow afternoon.

More news about the first annual CppCon that was announced last week:

CppCon 2014 Call for Submissions

CppCon is the annual, week-long face-to-face gathering for the entire C++ community. The conference is organized by the C++ community for the community and so we invite you to present.

Have you learned something interesting about C++, maybe a new technique possible in C++11? Or perhaps you have implemented something cool related to C++, maybe a new C++ library? If so, consider sharing it with other C++ enthusiasts by giving a talk at CppCon 2014. Submissions deadline is May 15 with decisions sent by June 13. For topic ideas, possible formats, and submission instructions, see the Submissions page.

Note that speakers get free registration to attend the whole conference.

I strongly encourage you to present – not “even if” you’ve never presented before, but “especially if” you haven’t. At 5 days x ~5 tracks x ~6 full-length talks per day, this is a big conference with a lot of room for half-length (30 min), full-length (60 min) and multi-hour formal talks (this is in addition to Lightning Talks, which will be arranged later).

For an idea of talks, from the Submissions page:

We are open to any topic that will be of interest to a mainstream C++ audience. Below are some ideas.

  • C++11
  • C++ libraries and frameworks of general interest
  • C++14 and new standardization proposals
  • Parallelism/multi-processing
  • Concepts and generic programming
  • Functional programming
  • High performance computing
  • Software development tools, techniques, and processes for C++
  • Practical experiences using C++ in real-world applications
  • Industry-specific perspectives: mobile and embedded systems, game development, high performance trading, scientific programming, robotics, etc.

I know a number of people who are already planning to submit talks, and I am certain we will get talks on all these topics, and likely more.

As for me, I’m going to go propose a talk on lock-free programming now… everyone should have fun with lock-free mail slots and linked lists, and know when to worry about the ABA problem (and know how to solve it in portable C++11 code).

What should you do next?

If you have a talk idea, run don’t walk to submit a talk – but don’t register for the conference yet as you will get free registration for the conference if your talk is accepted.

Otherwise, register today! The first 100 to register get the Super Early Bird rate of $695 for the whole conference, and registration got off to a strong start since it opened last week – a good number of first-100 places are still available. This is the coolest and most informative event for C++ in nearly 20 years, and whether you’re a C++ novice or an expert you are going to have a great time and learn a lot of practical information and skills you can use on your project today.

I’m really excited about this event!

Note that the first 100 registrations get a big discount – pasting from the “registration” page:

Regular registration fee is $995 but the first 100 attendees can take advantage of Super Early Bird registration and pay only $695. After that, the Early Bird registration fee is $845 and is valid until the 1st of June. …

The announcement went live four hours ago, and the first registrations have already started to come in.

The full text of today’s announcement follows:


CppCon 2014 Registration Open

Opening Keynote by Bjarne Stroustrup
September 7–12, 2014
Bellevue, Washington, USA

Registration is now open for CppCon 2014 to be held September 7–12, 2014 at the Meydenbauer Center in Bellevue, Washington, USA. The conference will start with the keynote by Bjarne Stroustrup titled “Make Simple Tasks Simple!

CppCon is the annual, week-long face-to-face gathering for the entire C++ community. The conference is organized by the C++ community for the community. You will enjoy inspirational talks and a friendly atmosphere designed to help attendees learn from each other, meet interesting people, and generally have a stimulating experience. Taking place this year in the beautiful Seattle neighborhood and including multiple diverse tracks, the conference will appeal to anyone from C++ novices to experts.

What you can expect at CppCon:

  • Invited talks and panels: the CppCon keynote by Bjarne Stroustrup will start off a week full of insight from some of the world’s leading experts in C++. Still have questions? Ask them at one of CppCon’s panels featuring those at the cutting edge of the language.
  • Presentations by the C++ community: What do embedded systems, game development, high frequency trading, and particle accelerators have in common? C++, of course! Expect talks from a broad range of domains experts focused on practical C++ techniques, libraries, and tools.
  • Lightning talks: Get informed at a fast pace during special sessions of short, less formal talks. Never presented at a conference before? This is your chance to share your thoughts on a C++-related topic in an informal setting.
  • Evening events and “unconference” time: Relax, socialize, or start an impromptu coding session.

CppCon’s goal is to encourage the best use of C++ while preserving the diversity of viewpoints and experiences, but other than that it is non-partisan and has no agenda. The conference is a project of the Standard C++ Foundation, a not-for-profit organization whose purpose is to support the C++ software developer community and promote the understanding and use of modern, standard C++ on all compilers and platforms.

S&S Postscript

PS on the previous post regarding Stroustrup & Sutter:

I had asked the organizers whether it would be possible to get a piano in the room.

I just learned a few minutes ago that they will be able to arrange a baby grand. Sweet!

This is going to be fun…

It has occurred to me that I never announced this event here…

In two weeks, Bjarne and I will be doing a two-day Stroustrup & Sutter on C++ seminar in the San Francisco Bay area. It has been several years since the last S&S event, so Bjarne and I are really looking forward to this.

Super C++ Tutorial: Stroustrup & Sutter on C++

EE Live!
March 31 – April 1, 2014
McEnery Convention Center
San Jose, CA, USA


The organizers have kindly made sure they can expand the room, so seats are still available. Sorry for the short notice here on this blog.

Using C++ atomics: Lock-Free Algorithms and Data Structures in C++

Here’s one interesting content update: The sessions page lists our talks, including a talk by me with the title “Three Cool Things in C++ Concurrency,” which is pronounced “I hadn’t decided what exactly I wanted to talk about by the time I had to submit the session description.”

I have now decided, and the talk will be entirely on how to design and write lock-free algorithms and data structures using C++ atomic<> – something that can look deceptively simple, but contains very deep topics. (Important note: This is not the same as my “atomic<> Weapons” talk; that talk was about the “what they are and why” of the C++ memory model and atomics, and did not cover how to actually use atomics to implement highly concurrent algorithms and data structures.)

This talk is about the “how to use them successfully” part of atomics, including:

  • Best practices and style for using atomic<>s
  • Three examples, including lock-free mail slots and iterations of a lock-free linked list, all in portable Standard C++
  • Defining and applying the different levels of “lock-freedom” (wait-free, lock-free, obstruction-free) to develop highly concurrent algorithms and data structures
  • Explaining and applying key concepts including especially: linearizability; trading off concurrency vs. promptness; and trading off concurrency vs. throughput/utilization
  • Demonstrating and solving the ABA problem, with clean and simple code – that’s right, did you know that in C++11 you can solve this without relying on esoterica like double-wide CAS (which isn’t always available) or hazard pointers (which are deeply complex) or garbage collection (which isn’t in the C++ standard… yet)?

A few of you may have seen part of this material in the few times I’ve taught the extended four-day version of my Effective Concurrency course. This version of the material is significantly updated for C++11/14 and also contains new material never before seen even if you did take in the four-day EC course – including that instead of leaving the slist example as a cliffhanger, I present an actual complete solution for the slist example that is (a) correct and (b) can be entirely written using portable Standard C++11. It’s always nice to end with a solution you can actually use, instead of just an open problem cliffhanger…

I’m looking forward to seeing many of you in San Jose in two weeks!


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