Why C++ Sails When the Vasa Sank -- Scott Meyers

By Blog Staff | Jun 23, 2014 10:24 AM | Tags: intermediate basics

Now available online, a nice talk by Scott Meyers about why modern C++ is alive and continues to enjoy life and growth:

Why C++ Sails When the Vasa Sank

by Scott Meyers

The Vasa was a 17th-century Swedish warship which suffered such feature creep during construction that it sank shortly after leaving the harbour on its maiden voyage. In the early 1990s, the C++ standardisation committee adopted the Vasa as a cautionary tale, discouraging prospective language extensions with "Remember the Vasa!" Yet C++ continued to grow, and by the time C++ was standardised, its complexity made the Vasa look like a rowboat.

The Vasa sank, however, while C++ cruised, and it looks likely to continue doing so even as the latest revised standards (C++11 and C++14) add dozens of new features, each with its own idiosyncrasies. Clearly, C++ has gotten some important things right. In this talk, Scott Meyers considers the lessons to be learned from the ongoing success of a complex programming language that's over 30 years old, yet very much alive and kicking.

Masking a Class in Boost Graph, Part 3: Finding the Path -- Vadim Androsov

By Blog Staff | Jun 16, 2014 07:19 AM | Tags: intermediate

Part 3 of Vadim's experience report about using Boost's graph support in an existing game app:

Masking a Class in Boost Graph. Part 3: Finding the Path

by Vadim Androsov

From the article:

In the previous articles of the series we’ve reviewed the adaptive process of the square game field for concepts of boost graphs. Now we’ll consider the process of finding the path in the square field. Implementation of boost search allows adapting the algorithm quite accurately. In this article we’ll provide just one example of such parameterization – an ability to create various lengths of graph edges. ...

Lightweight HTTP Server in less than 40 Lines on libevent and C++11 -- NYM

By Blog Staff | Jun 3, 2014 11:18 AM | Tags: intermediate concurrency

Fresh on Kukuruku:

Lightweight HTTP Server in less than 40 Lines on libevent and C++11

by NYM

From the article:

Looking through programming articles sometimes I see posts about creating your own HTTP server. I am most interested in C++ so I often read blogs about it. After looking them through you could easily write you own web server “on sockets” using boost.asio or something else. I also examined libevent and libev. Each of them has its advantages. Libevent is of great interest to me for developing a small HTTP server. Considering some innovations in C++11 the code becomes much more space-efficient and allows for the creation of a basic HTTP server in less than 40 lines.

Ref-qualifiers -- Andrzej Krzemieński

By Blog Staff | Jun 3, 2014 06:40 AM | Tags: intermediate

The latest from the desk of Andrzej:

Ref-qualifiers

by Andrzej Krzemieński

From the article:

In this post I want to describe a small language feature added in C++11 that, although essential for full value semantics support, is often neglected in tutorials and in compiler implementations....

Writing min function, part 1: The rise of Concepts -- Fernando Pelliccioni

By Fernando Pelliccioni | May 28, 2014 07:32 PM | Tags: intermediate

[Ed: Note that this article series is not (yet) about C++ code, but it promises to go there and it has an interesting pedigree in its generic programming design analysis (Alex Stepanov) and reviewers (several ISO C++ participants including Andrzej Krzemienski and Dean Michael Berris.]

Writing min function, part 1: The rise of Concepts

by Fernando Pelliccioni

From the article:

This is the first in a series of articles in which I want to transmit what I learned (or what I think I learned) from the books, papers, lectures of Alexander Stepanov.

These are the lessons that Alex gives us, and I want to show them in this series:

• Specify our algorithms correctly
• Programming must be based on a solid mathematical foundation
• Designing our API’s consistently
• Not always the library implementations provided by the programming languages we use are correct, even though they are designed by “experts”.
• The concept of Stability
• Generic programming, of course!

Ref-qualified member functions -- Alexander Kulikov

By Blog Staff | May 28, 2014 07:23 PM | Tags: intermediate basics

Today on Kukuruku:

Ref-qualified member functions

by Alexander Kulikov

From the article:

Today I’m going to tell you about a new and a little known (to my mind) C++ feature — reference-qualified member functions. I’ll tell about the rules of such functions overloading and, as an example of use, I’ll show you that with the help of ref-qualified you can try to improve the resource management scheme, which is implemented with the help of another C++ idiom — RAII.

Vector of Objects vs Vector of Pointers Updated -- Bartlomiej Filipek

By Blog Staff | May 22, 2014 07:30 AM | Tags: performance memory intermediate efficiency

More in the "contiguous enables fast" department:

Vector of Objects vs Vector of Pointers Updated

by Bartlomiej Filipek

From the article:

For 1000 particles we need on the average 2000 cache line reads! This is 78% more cache line reads than the first case! Additionally Hardware Prefetcher cannot figure out the pattern -- it is random -- so there will be a lot of cache misses and stalls.

In our experiment the pointer code for 80k of particles was more 266% slower than the continuous case.

ACCU 2014 talk slides now available

By Blog Staff | May 21, 2014 02:58 PM | Tags: intermediate

[Ed: Here's a candidate for the most hilarious thing you'll probably see today: Kevlin Henney's slide deck, including a link to this @netbat tweet.]

The recent ACCU 2014 was another resounding success, and many of the talk slides have now been posted. You can find them here:

Slides, Photos, Blogs via #accu2014 (accu.org)

Some fun C++ highlights with slides available include:

• Dietmar Kuhl · Performance Choices
• Howard Hinnant · Everything You Ever Wanted To Know About Move Semantics (and then some)
• Hubert Matthews · Where is C++ headed?
• Jonathan Wakely · There Ain't No Such Thing As A Universal Reference
• Jonathan Wakely · The C++14 Standard Library
• Kevlin Henney · Immutabilty FTW!
• Marshall Clow · C++ Undefined Behavior -- what is it, and why should I care?
• Olve Maudal · C++ Pub Quiz
• Pattabi Raman · Random number generation in C++ -- present and potential future
• Peter Sommerlad · C++14 an overview on the new standard for C++(11) programmers
• Steve Love · Range and Elevation -- C++ in a modern world
• ... and more (see the page).

CppCon: My Proposed Talks (Part 2) -- Herb Sutter

By Blog Staff | May 21, 2014 08:05 AM | Tags: intermediate experimental

Following up on Herb's three talk proposals posted yesterday, the other two titles and abstracts are now posted, this time of new talks (note: again, pending review and selection by the program committee, so this is not final -- they may or may not be selected if there is stronger material).

CppCon: My Proposed Talks (Part 2)

by Herb Sutter

From the post:

GC for C++, and C++ for GC: “Right” and “Wrong” Ways to Add Garbage Collection to C++ (1 to 2 hours)

"Garbage collection is essential to modern programming!" "Garbage collection is silly, who needs it!"

As is usual with extremes, both of these statements are wrong. Garbage collection (GC) is not needed for most C++ programs; we're very happy with determinism and smart pointers, and GC is absolutely penalizing when overused, especially as a default (or, shudder, only) memory allocator. However, the truth is that GC is also important to certain high-performance and highly-concurrent data structures, because it helps solve advanced lock-free problems like the ABA problem better than workarounds like hazard pointers.

This talk presents thoughts about how GC can be added well to C++, directly complementing (not competing with) C++'s existing strengths and demonstrating why, as Stroustrup says, "C++ is the best language for garbage collection."

 

Addressing C++’s #1 Problem: Defining a C++ ABI (1 hour)

"Why can't I share C++ libraries even between my own internal teams without using the identical compiler and switch settings?" "Why are operating system APIs written in unsafe C, instead of C++?" "Why can’t I use std::string in a public shared library interface; it's the C++ string, isn't it?!"

These and more perennial questions are caused by the same underlying problem: For various historical reasons, C++ does not have a standard binary interface, or ABI. Partial solutions exist, from the Itanium ABI which addresses only the language and only on some platforms, to COM and CORBA which do both less and far more than is needed.

It is deeply ironic that there actually is a way to write an API in C++ so that it has a de facto stable binary ABI on every platform: extern "C".

This session describes current work driven by the presenter to develop a standard C++ ABI. This does not mean having identical binaries on all platforms. It does mean tackling all of the above problems, including directly addressing the #1 valid reason to use C instead of C++, and removing a major obstacle to sharing binary C++ libraries in a modern way.

CppCon: My Proposed Talks (Part 1) -- Herb Sutter

By Blog Staff | May 20, 2014 07:24 AM | Tags: intermediate

With the CppCon talk submission deadline upon us, we're starting to get glimpses of the potential CppCon conference program. In today's post, Herb Sutter mentions three of his five talk proposals (note: pending review and selection by the program committee, so this is not final -- they may or may not be selected if there is stronger material).

CppCon: My Proposed Talks (Part 1)

by Herb Sutter

From the post:

Lock-Free Programming – or, How to Juggle Razor Blades (~2 hours)

Example-driven talk 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 or more 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)?

Standardization Update: C++14 and the Seven Dwarfs (1 hour)

Standardization has accelerated: By the time we meet at CppCon, C++14 might already be ratified. But that's only one of eight (so far) work items now in flight. In this session, I'll give a brief summary of the new features coming in C++14 itself, and then a tour of the seven (7) near-term separate Technical Specifications already underway – think of these as the "C++14 wave" of deliverables.

The ISO C++ committee has transitioned to a "decoupled" model where updated versions of the standard are published more frequently, while at the same time major pieces of work can progress and be published independently from the Standard itself and delivered asynchronously in the form of Technical Specifications (TS’s) that are separate from the main Standard and can later be incorporated into the Standard. Come to this session to see how this is helping both the standard and C++ compiler implementations near you stay current with the latest in C++.

The topics covered will be:

• C++14: What’s new in the new standard due this year
• File System TS: Portable file system access
• Library Fundamentals TS (small): string_view and optional<>
• Array Extensions TS: Language and library dynamic arrays
• Concepts Lite TS: Templates + constraints = ++usability and ++diagnostics
• Concurrency TS: Nonblocking futures (.then, .when_*), executors, and (maybe) await
• Parallelism TS: A whole new Parallel STL with both parallel and vector execution support
• One of:
      – Networking TS (small): IP addresses, URIs, byte ordering
      – Transactional Memory TS: Language and library extensions for transactional memory instead of mutexes for many kinds of concurrency control

This session will present an overview of each set of features, what it looks like and how to use it, and why it’s important for the standard and for your own portable C++ code.

Modern C++ Style: Idioms of C++11/14 (1 to 3 hours)

This session will cover modern and current C++ style, focusing on C++14. It will demonstrate how major features and idioms from C++98 are now entirely replaced or subsumed and should be used no more; how other major features and idioms have been dramatically improved to the point where your code is cleaner and safer and you’ll even think in a different style; and how pervasive styles as common as variable declarations are changed forever, and not just for style but for serious technical safety and efficiency benefits. For one thing, you’ll never look at auto the same way again – and if hearing that makes you worry, worry not, just attend the session to dig deep into the good reasons for the new reality.

Why C++14? Two reasons: First, it really does "complete C++11" with small but important consistency features like generic lambdas and make_unique that let us teach modern C++ style with fewer “except for” footnotes. Second, C++14 “is” C++ for the next several years and it’s real; it is feature-complete and in the final stages of standardization, and more importantly we are already seeing near-complete conforming implementations becoming widely available around the same time C++14 is expected to be formally published.

C++14 is a small but important improvement on C++11 that really does complete the language. What this means is that we’re going to have a complete and simpler set of idioms and styles to learn and use.