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CppCon 2015 Program Highlights, 11 of N

By Adrien Hamelin | Sep 9, 2015 09:00 AM | Tags: None

The CppCon 2015 conference program has been posted for the upcoming September conference. We’ve received requests that the program continue to be posted in “bite-sized” posts, a few sessions at a time, to make the 100+ sessions easier to absorb, so here is another set of talks. This series of posts will conclude once the entire conference program has been posted in this way.

 

C++, it is also a language that we like to discover and master always more.

The following interrelated CppCon 2015 talks tackle these issues and more (part 2).

In this post:

  • Concurrency TS: The Editor's Report
  • `for_each_argument` explained and expanded
  • std::allocator Is to Allocation what std::vector Is to Vexation
  • <functional>: What's New, And Proper Usage
  • Type Traits - what are they and why should I use them?

 

Concurrency TS: The Editor's Report by Artur Laksberg, Software Engineer, Microsoft

In this presentation we will talk about the new C++ concurrency features that have been included in the Concurrency Technical Specification.

The TS should be of interest to anyone writing concurrent code in C++. The proposal includes improved futures for wait-free composition of asynchronous operations (including their relationship with C++ 'await'), new synchronization constructs as well as atomic smart pointers.


`for_each_argument` explained and expanded by Vittorio Romeo

During January 2015, Sean Parent posted a very interesting short piece of code on Twitter. The code iteratively iterates at compile-time over any number of function arguments, forwarding them one by one to a callable object.

How does this code work? What are the possible use cases? Can we make it even more generic and useful?

My talk answers all of the questions above, using independently compiled chronologically sequential code segments that show the audience the analysis and improvement process of `for_each_argument`.


std::allocator Is to Allocation what std::vector Is to Vexation by Andrei Alexandrescu, Founder, D Language Foundation

std::allocator has an inglorious past, murky present, and cheerless future. STL introduced allocators as a stop gap for the now antiquated segmented memory models of the 1990s. Their design was limited and in many ways wasn't even aiming at helping allocation that much. Because allocators were there, they simply continued being there, up to the point they became impossible to either uproot or make work, in spite of valiant effort spent by the community.

But this talk aims at spending less time on poking criticism at std::allocator and more on actually defining allocator APIs that work.

Scalable, high-performance memory allocation is a topic of increasing importance in today's demanding applications. For such, std::allocator simply doesn't work. This talk discusses the full design of a memory allocator created from first principles. It is generic, componentized, and composable for supporting application-specific allocation patterns.


<functional>: What's New, And Proper Usage by Stephan T. Lavavej, Senior Software Engineer, Microsoft

<functional> gained lots of machinery in C++11, with further changes in C++14 and C++17. This talk will cover what's new in 11/14/17, focusing on how to use it properly. For example, you've probably used std::function, but do you know the criteria for activating the Small Functor Optimization? (It's not just being small!) We'll also look at bind(), mem_fn(), C++17's invoke(), and more.


Type Traits - what are they and why should I use them? by Marshall Clow, Qualcomm

In this talk, I will answer the questions, "What are type traits?" and "Why are type traits useful?", along with some examples of why when when they should be used.

CppCon 2015 Program Highlights, 10 of N

By Adrien Hamelin | Sep 8, 2015 09:00 AM | Tags: None

The CppCon 2015 conference program has been posted for the upcoming September conference. We’ve received requests that the program continue to be posted in “bite-sized” posts, a few sessions at a time, to make the 100+ sessions easier to absorb, so here is another set of talks. This series of posts will conclude once the entire conference program has been posted in this way.

 

C++, it is also a language that we like to discover and master always more.

The following interrelated CppCon 2015 talks tackle these issues and more (part 1).

In this post:

  • Tuning C++: Benchmarks, and Compilers, and CPUs! Oh My!
  • Value Semantics: It ain't about the syntax!, Part I and Part II
  • Five amazing things you couldn't imagine C++ can do
  • C++ Atomics: The Sad Story of memory_order_consume: A Happy Ending at Last?
  • A C++14 approach to dates and times

 

Tuning C++: Benchmarks, and Compilers, and CPUs! Oh My! by Chandler Carruth, C++ Language and Compiler Lead, Google

A primary use case for C++ is low latency, low overhead, high performance code. But C++ does not give you these things for free, it gives you the tools to control these things and achieve them where needed. How do you realize this potential of the language? How do you tune your C++ code and achieve the necessary performance metrics?

This talk will walk through the process of tuning C++ code from benchmarking to performance analysis. It will focus on small scale performance problems ranging from loop kernels to data structures and algorithms. It will show you how to write benchmarks that effectively measure different aspects of performance even in the face of advanced compiler optimizations and bedeviling modern CPUs. It will also show how to analyze the performance of your benchmark, understand its behavior as well as the CPUs behavior, and use a wide array of tools available to isolate and pinpoint performance problems. The tools and some processor details will be Linux and x86 specific, but the techniques and concepts should be broadly applicable.


Value Semantics: It ain't about the syntax!, Part I and Part II by John Lakos, Software Infrastructure Manager, Bloomberg LP

When people talk about a type as having *value* *semantics*, they are often thinking about its ability to be passed to (or returned from) a function by value. In order to do that, the C++ language requires that the type implement a copy constructor, and so people routinely implement copy constructors on their classes, which begs the question, "Should an object of that type be copyable at all?" If so, what should be true about the copy? Should it have the same state as the original object? Same behavior? What does copying an object mean?! By *value* *type*, most people assume that the type is specifically intended to represent a member of some set (of values). A *value-semantic* *type*, however, is one that strives to approximate an abstract *mathematical* type (e.g., integer, character set, complex-number sequence), which comprises operations as well as values. When we copy an object of a value-semantic type, the new object might not have the same state, or even the same behavior as the original object; for proper value-semantic types, however, the new object will have the same *value*. In this talk, we begin by gaining an intuitive feel for what we mean by *value* by identifying *salient* *attributes*, i.e., those that contribute to value, and by contrasting types whose objects naturally represent values with those that don't. After quickly reviewing the syntactic properties common to typical value types, we dive into the much deeper issues that *value* *semantics* entail. In particular, we explore the subtle *Essential* *Property* *of* *Value*, which applies to every *salient* mutating operation on a value-semantic object, and then profitably apply this property to realize a correct design for each of a variety of increasingly interesting (value-semantic) classes.


Five amazing things you couldn't imagine C++ can do by Sasha Goldshtein

Modern C++ is incredibly flexible. It's truly the multi-paradigm language Bjarne Stroustrup envisioned. In this talk, we will explore five functions or small libraries that make use of modern C++'s amazing features. Among them: compile-time- and runtime-safe printf, automatic recursive serialization of containers, a simple but complete parallelism framework using only portable C++, and two others to keep you motivated.


C++ Atomics: The Sad Story of memory_order_consume: A Happy Ending at Last? by Paul McKenney, Distinguished Engineer, IBM Linux Technology Center

One of the big advantages of C++ atomics is that developers can now let the compiler know about the intent behind their multi-threaded synchronization mechanisms. At least they can tell the compiler as long as the synchronization mechanism in question is not RCU. You see, all production compilers promote RCU's memory_order_consume to memory_order_acquire. Although this promotion does ensure correctness, it also ensures the additional overhead of memory-barrier instructions on weakly ordered systems and of needlessly suppressed compiler optimizations on all systems.

All previous attempts to resolve this issue have foundered on either standard-committee reluctance to eviscerate the standard for a special case, compiler-writer reluctance to eviscerate their compilers for a special case, and kernel-developers reluctance to eviscerate their source base for late-to-the-party compiler support.

But now there is a glimmer of hope in the guise of a small set of small patches to the Linux kernel that eliminate the most challenging use cases. Will this hope be realized? Come to this talk to here the story, which by September will hopefully have a happy ending!


A C++14 approach to dates and times by Howard Hinnant, Senior Software Engineer, Ripple Labs

A new date and date/time library designed for C++14 is presented. This library stresses ease of use, easy-to-read code, catching common errors at compile time, and uncompromising run-time performance.

The design starts with the C++11 std::chrono library, and extends it into the realm of calendars, giving a seamless experience built upon chrono::system_clock::time_point, the durations you already know such as chrono::hours and nanoseconds. Functionality that allows easy and efficient conversions between the std::chrono types and year/month/day - hh::mm::ss data structures is presented.

When dates (and times) are known at compile-time (e.g. leap second transitions), all computations are available at compile time (constexpr). When only parts of a date are known at compile time, run-time efficiencies are still gained by compile-time computing parts of the date.

The syntax of the library is built around a few easy-to-learn rules, and strictly checked at compile time. This makes it easy to learn, and very forgiving for the novice.

A third way to use boost::serialization

By Meeting C++ | Sep 8, 2015 06:54 AM | Tags: intermediate boost advanced

The 10th installment in my series about writing applications with Qt and boost:

A third way to use boost::serialization

by Jens Weller

From the article:

The 10th part of my series about writing applications with Qt and boost is about using boost::serialization. The last part was about how to create the basic structure for a project with boost::filesystem, and how to use boost::filesystem to index folders. But there is a lot of data that just isn't able to be represented as single files, how to store it?

Originally I planned to use a database, as I already have some code handling the SQL queries nicely for me and most of my other applications currently also use this to store their data. Thats why most of my classes from the first day on had an id field, just to enable them to refer to an instance stored in a database. But then, if I could get around using a database, by simply just storing my data in a file, things would be easier, and my code wouldn't need to be scattered with SQL queries. If I couldn't find a reasonable approach, I still could opt for a database anyways.

CppCast Episode 25: Software Transactional Memory with Brett Hall

By robwirving | Sep 4, 2015 06:09 AM | Tags: None

Episode 25 of CppCast the only podcast for C++ developers by C++ developers. In this episode Rob and Jason are joined by Brett Hall to discuss Software Transactional Memory.

CppCast Episode 25: Software Transactional Memory with Brett Hall

by Rob Irving and Jason Turner

About the interviewee:

Brett Hall is the lead engineer on Dynamics, a desktop application that collects and analyzes data from the light scattering instruments built by Wyatt technology. Prior to joining Wyatt, Brett worked in web application development, remote sensing, and spent a summer in the games industry. He holds a PhD in physics from the University of California, Santa Barbara. Part of his research work involved using C++ to solve the PDE systems generated by the rest of the research. All told he’s been using C++ for around 20 years now. These days the bulk of his programming interest is in concurrency and parallelism. When not programming he’s usually hanging out with his family and/or mountain biking.

C++ User Group Meetings in September

By Meeting C++ | Sep 3, 2015 04:38 AM | Tags: community

The monthly listing of C++ User Group Meetings:

C++ User Group Meetings in September

by Jens Weller

The list of Meetings:

9.9 C++ UG Utah - Regular Monthly Meeting
9.9 C++ UG San Francisco/ Bay area - Presentation and Q&A
9.9 C++ UG Washington, DC - Q & A / Info Sharing 10.9 C++ UG Dresden - Scripting in C++
14.9 C++ UG Denver - Denver Tech Center C++ Developers
14.9 C++ UG Bristol - Tim Perry
14.9 C++ UG Zentralschweiz - Coding Dojo
16.9 C++ UG Düsseldorf - Treffen der C++ User Gruppe NRW
16.9 C++ UG North West/Seattle - The BBC micro: bit and C++
17.9 C++ UG Chicago - "Cross-compiling to C++" and "Can you make me more productive
21.9 C++ UG Austin - North Austin Monthly C/C++ Pub Social
23.9 C++ UG San Francisco/ Bay area - Workshop and Discussion Group
23.9 C++ UG Washington, DC - Q & A / Info Sharing
24.9 C++ UG Rhein-Neckar - C++ Usergroup Meeting
24.9 C++ UG Bremen - C++ - Vorstellung eines Frameworks für den Integrationtest
24.9 C++ UG Arhus - Libreoffice Hackfest
30.9 C++ UG San Francisco/ Bay area - CppCon Trip Report

CppCon 2015 Program Highlights, 9 of N

By Adrien Hamelin | Sep 2, 2015 09:00 AM | Tags: None

The CppCon 2015 conference program has been posted for the upcoming September conference. We’ve received requests that the program continue to be posted in “bite-sized” posts, a few sessions at a time, to make the 100+ sessions easier to absorb, so here is another set of talks. This series of posts will conclude once the entire conference program has been posted in this way.

 

C++ is not composed of only a language. It is also powerful librairies, helping us to get the best fonctionnalities.

The following interrelated CppCon 2015 talks tackle these issues and more (part 2).

In this post:

  • Rcpp: Seamless R and C++ Integration
  • Mantid, A C++ framework for the reduction and analysis of neutron scattering data
  • Integrating generators EDSL's for Boost.Spirit X3
  • 3D Face Tracking and Reconstruction using Modern C++
  • Using Spirit X3 to Write Parsers
  • Boost Units Library for Correct Code

 

Rcpp: Seamless R and C++ Integration by Matt P. Dziubinski, Assistant Professor, Aalborg University

R is an open-source statistical language designed with a focus on data analysis. While its historical roots are in statistical applications, it is currently experiencing a rapid growth in popularity in all fields where data matters: from data science, through bioinformatics and finance, to machine learning. Key strengths contributing to this growth include its rich libraries ecosystem (over 6 thousands packages at the moment of writing) – often authored by the leading researchers in the field, providing early access to the latest techniques; beautiful, high-quality visualizations – supporting seamless exploratory data analysis and producing stunning presentations; all of this available in an interactive environment resulting in high productivity through fast iteration times.

At the same time, there are no free lunches in programming: the dynamic, interactive nature of R does have its costs, including a significant impact on run-time performance. In an era of growing data sizes and increasingly realistic models this concern is only becoming more important.

In this talk we provide an introduction to Rcpp – a library allowing smooth integration of R with C++, combining the productivity benefits of R for data science together with the performance of C++. First released in 2005, today it’s the most popular language extension for R -- used by over 400 packages. We'll also discuss challenges (as well as possible solutions) involved in integrating modern C++ code, and demonstrate the usage of popular C++ libraries in practice. We’ll conclude the talk with the RInside package allowing to embed R in C++.


Mantid, A C++ framework for the reduction and analysis of neutron scattering data by Steven Hahn, Data Analysis Software Engineer, Oak Ridge National Laboratory

Today one of the most important barriers between performing an experiment and publishing the results is the complex and time-consuming effort that individual researchers apply to data reduction and analysis. In a neutron experiment one must relate measured counts to a physically meaningful four-dimensional scattering function. While the first neutron scatters had to manually setup their instrument and record neutron counts – in handwriting – one single point at a time, users at a modern time of flight spectrometer rapidly collect hundreds of gigabytes of data in less than one day. High performance software is now a necessity. Rapid reduction, analysis and visualization provide feedback for users, helping them make optimal use of limited beam time. Software must also be accessible to and customized by users with a wide range of abilities and interests in programming. In this talk, I will discuss Mantid-(the Manipulation and Analysis Toolkit for Instrument Data), which is the framework designed for the reduction and analysis of data acquired at muon and neutron sources. It is a partnership between multiple user facilities including Rutherford Appleton Laboratory, Oxfordshire, UK, Oak Ridge National Laboratory, Tennessee, USA and the European Spallation Source, Scandinavia. The core of the Mantid Framework is written in C++ with the user interacting via a GUI or python bindings. I will describe real-world cross-platform situations we have encountered while supporting Mantid on Linux, OS X and Windows. This plus a climate that values stability over the latest operating systems and compilers creates challenges to utilizing new language and library features available in C++11/14. To better exploit parallelism on all of the supported platforms, we are wrapping parallel loops so that different implementations can be chosen at compile time. Considerable portions of Mantid provide domain-specific user interfaces to cross-platform libraries. One example is 3D visualization of the large multidimensional datasets generated in Mantid. Our approach utilizes the application widgets and rendering libraries from ParaView. Mantid provides plugins specifically designed for the Mantid data structures. A custom interface for visualization can be started within Mantid, creating a seamless environment for novice users not comfortable with the ParaView workflow.

This research at ORNL’s High Flux Isotope Reactor and Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, US Department of Energy.


Integrating generators EDSL's for Boost.Spirit X3 by Felipe Magno de Almeida, Owner, Expertise Solutions

Based on the presentation I made on C++Now 2015 for Developing EDSL's for Boost.Spirit V2, present the development of generators for Boost.Spirit X3 (next version of boost spirit) and how that can be used for higher abstraction EDSL's while, through template metaprogramming, create parsers and generators automatically from the same grammar, using CORBA format as an example, while dealing with endianness, alignment and asymmetric grammars. This work is based on the library mORBid (https://github.com/expertisesolutions/mORBid) and (https://github.com/expertisesolutions/giop).


3D Face Tracking and Reconstruction using Modern C++ by Patrik Huber, PhD student in computer vision, University of Surrey

In this talk, I will present my work in computer vision, namely landmark detection and 3D face tracking, and the two C++ libraries that were developed in the process. The first part of the talk will give an introduction to detecting facial landmark points and work through a hello-world code example that presents and uses the superviseddescent library, a cross-platform library for cascaded regression that can be used to solve problems like landmark detection or pose estimation. The second part of the talk will present an approach that uses the found landmarks from the first part to use a 3D face model to track a person's face. With the library presented in the process, we hope to make 3D models easier to use and more widespread in the community. Both libraries are designed to be lightweight and simple to use, and try to follow modern C++11/14 programming paradigms. The talk concludes with my views on code sustainability in academia and a wish list of standard library features for computer vision.


Using Spirit X3 to Write Parsers by Michael Caisse, Ciere Consulting

Parsing is a common problem in many domains. The complexity of using a library often pushes developers to ad-hoc solutions utilizing std::string manipulations, regular expressions, or nested if/switch statements. Most “quick hack” implementations are unmaintainable.

Spirit provides a Domain Specific Embedded Language (DSEL) that allows grammars to be described in a natural and declarative manner just like writing PEG or EBNF directly in your C++ code. X3 is the third major release of the Spirit library and improves both compile and run times while simplifying the much of the library.

In this tutorial session you will be introduced to Spirit X3, attribute parsing, and variety of tips to writing efficient and maintainable parsers. We will build a JSON parser during the session to illustrate techniques and usage of the library. This session is applicable toward anyone needing to parse data.


Boost Units Library for Correct Code by Robert Ramey, Proprietor, Robert Ramey Software Development

I will give a presentation on the Boost Units library.

This library implements a zero runtime facility for performing dimensional analysis checking and automatic units conversion on C++ expressions. I have found this indispensable for coding scientific programs involving a variety of complex physical units. The documentation of the Boost Units library is totally complete and accurate, but totally inpenetrable. I had to spend way too much time figuring out how to use this. By attending this meeting, you're going to avoid this pain and just get the benefit of simpler programs that contain fewer bugs.