CppCast Episode 162: The Art of C++ Libraries with Colin Hirsch

By robwirving | Aug 10, 2018 09:14 AM | Tags: None

Episode 162 of CppCast the only podcast for C++ developers by C++ developers. In this episode Rob and Jason are joined by Colin Hirsch to discuss his work on The Art of C++ collection of libraries including PEGTL, json and more.

CppCast Episode 162: The Art of C++ Libraries with Colin Hirsch

by Rob Irving and Jason Turner

About the interviewee:

Dr. Colin Hirsch studied Computer Science at the University of Technology in Aachen, Germany in 1993 and later got a PhD in Mathematics from the same university. He worked for two years as a consultant for T-Mobile, developing back-end server applications in C++ and Lua. Later Colin moved to Italy, opened his own business and continued working for T-Mobile (now Deutsche Telekom) as well as working for some other interesting projects like Greenpeace and the Austrian ministry of ecology.

In his free time he enjoys photography, being in nature, science fiction and spending time with his daughter.

CppCon 2017: Practical Techniques for Improving C++ Build Times--Dmitry Panin

By Adrien Hamelin | Aug 8, 2018 12:39 PM | Tags: efficiency

Have you registered for CppCon 2018 in September? Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2017 for you to enjoy. Here is today’s feature:

Practical Techniques for Improving C++ Build Times

by Dmitry Panin

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

Slow builds block all C++ developers from the work being done. At Facebook we have a huge codebase, where the time spent compiling C++ sources grows significantly faster than the size of the repository. In this talk we will share our practical experience optimizing build times, in some cases from several hours to just a few minutes. The majority of the techniques are open sourced or generic and can be immediately applied to your codebase.

Facebook strives to squeeze build speed out of everything: starting from a distributed build system, through the compiler toolchain and ending with code itself. We will dive into different strategies of calculating cache keys, potential caching traps and approaches to improve cache efficiency. We tune the compiler, specifically with compilation flags, profile data and link time options. We will talk about the benchmarks we use to track improvements and detect regressions and what challenges we face there. Finally, you will learn about our unsuccessful approaches with an explanation of why they didn't work out for us.

CppCon 2017: Enough x86 Assembly to Be Dangerous--Charles Bailey

By Adrien Hamelin | Aug 6, 2018 01:39 PM | Tags: community

Have you registered for CppCon 2018 in September? Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2017 for you to enjoy. Here is today’s feature:

Enough x86 Assembly to Be Dangerous

by Charles Bailey

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

This tutorial is an introduction to x86 assembly language aimed at C++ programmers of all levels who are interested in what the compiler does with their source code.

C++ is a programming language that cares about performance. As with any technology, a deep understanding of C++ is helped by knowledge of the layer below, and this means knowledge of assembly language. Knowing what the compiler does with your source code and the limitations under which it operates can inform how you design and write your C++.

We learn how to generate, inspect and interpret the assembly language for your C++ functions and programs. We take a short tour of common assembly instructions and constructs, and discover why extreme caution should be exercised if we are trying to infer performance characteristics from a simple inspection of assembly code.

Starting with a simple `operator+` for a user-defined class, we take a look at how interface and implementation choices affect the generated assembly code and observe the effect of copy elisions and related optimizations that compilers commonly perform.

CppCast Episode 161: Expectations and Exceptions with Simon Brand

By robwirving | Aug 3, 2018 08:01 PM | Tags: None

Episode 161 of CppCast the only podcast for C++ developers by C++ developers. In this episode Rob and Jason are joined by Simon Brand to discuss his upcoming CppCon talks covering exceptions, value wrappers, debuggers and more.

CppCast Episode 161: Expectations and Exceptions with Simon Brand

by Rob Irving and Jason Turner

About the interviewee:

Simon is a GPGPU toolchain developer at Codeplay Software in Edinburgh. He turns into a metaprogramming fiend every full moon, when he can be found bringing compilers to their knees with template errors and debating undefined behaviour on the C++ Slack channel. He co-organises the Edinburgh C++ user group and contributes to various programming standards bodies.

Outside of programming, he enjoys experimental films, homebrewing, and board games.

CppCon 2017: How to Write Effective Documentation for C++ Libraries...--Robert Ramey

By Adrien Hamelin | Aug 3, 2018 01:18 PM | Tags: community

Have you registered for CppCon 2018 in September? Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2017 for you to enjoy. Here is today’s feature:

How to Write Effective Documentation for C++ Libraries...

by Robert Ramey

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

With the success of GitHub, everybody and his brother is a library developer. Programmers love to create code, upload it to GitHub and hope for immortality. Most projects get only the most cursory examination before being passed over by users. Why is that? GitHub considered the problem.

GitHub just published its 2017 Open Source Survey. The popular social coding service surveyed over 5,500 members of its community, from over 3,800 projects on github.com. It also spoke to 500 coders working on projects from outside the GitHub ecosystem. The Open Source Survey asked a broad array of questions. One that caught my eye was about problems people encounter when working with, or contributing to, open source projects. An incredible 93 percent of people reported being frustrated with “incomplete or confusing documentation”. see https://thenextweb.com/dd/2017/06/02/...

Even the most experienced and dedicated software developers can't do it. This can be confirmed by looking over recent reviews of Boost libraries. The most common complaint is that the documentation isn't useable.

Programmers love their stuff and hope to get people to use it, why don't they fix their documentation? The reason is simple: They don't know how.

Problems

a) It's tedious and boring to write
b) Developers don't know what to include and what to exclude
c) Tools make things harder
d) Regardless of the amount of effort invested, the end result is usually of little or no value.

This presentation will present a "Cookbook" and demonstration for creating documentation. Using this method will

a) Much diminish the tedium of the task.
b) Help improve to the quality of library design and implementation
c) Create something that is useful to the library user.

We will touch upon tools like Doxygen, etc. But this is only a small portion of the presentation. We use them so they deserve mention. But they don't cause the problem, and they don't solve it either.

CppCon 2017: How to Write a Custom Allocator--Bob Steagall

By Adrien Hamelin | Aug 1, 2018 12:54 PM | Tags: stl performance

Have you registered for CppCon 2018 in September? Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2017 for you to enjoy. Here is today’s feature:

How to Write a Custom Allocator

by Bob Steagall

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

You'd like to improve the performance of your application with regard to memory management, and you believe this can be accomplished by writing a custom allocator. But where do you start? Modern C++ brings many improvements to the standard allocator model, but with those improvements come several issues that must be addressed when designing a new allocator.

This talk will provide guidance on how to write custom allocators for the C++14/C++17 standard containers. It will cover the requirements specified by the standard, and will describe the facilities provided by the standard to support the new allocator model and allocator-aware containers. We'll look at the issues of allocator identity and propagation, and examine their implications for standard library users, standard library implementers, and custom allocator implementers. We'll see how a container uses its allocator, including when and how a container's allocator instance propagates. This will give us the necessary background to describe allocators that implement unusual semantics, such as a stateful allocator type whose instances compare non-equal. Finally, the talk will provide some guidelines for how to specify a custom allocator's public interface based on the semantics it provides.

CppCon 2017: CNL: A Compositional Numeric Library--John McFarlane

By Adrien Hamelin | Jul 30, 2018 11:11 AM | Tags: community

Have you registered for CppCon 2018 in September? Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2017 for you to enjoy. Here is today’s feature:

CNL: A Compositional Numeric Library

by John McFarlane

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

CNL is a numerics library born out of efforts to standardize fixed-point arithmetic.
It provides number types which increase precision, enforce correctness and maintain efficiency.
And by designing these types with composability in mind, the library aims to do for integers what the STL does for pointers.

This introductory talk will show potential users how they can benefit from using CNL in a wide variety of applications. Firstly, the individual components will be illustrated using straightforward examples. Then we'll see how these components slot together to produce powerful new types. Finally I'll detail the steps necessary to adapt existing types to work within the CNL framework.

Along the way, I hope to share some of the insights I've gained while learning about literal types including: why you shouldn't mess with `int` if you want zero-cost abstractions; how C++ is getting better at supporting new number types and my hopes for the forthcoming Numeric TS.

CppCon 2017: Building C++ Modules--Boris Kolpackov

By Adrien Hamelin | Jul 25, 2018 12:30 PM | Tags: experimental community

Have you registered for CppCon 2018 in September? Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2017 for you to enjoy. Here is today’s feature:

Building C++ Modules

by Boris Kolpackov

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

C++ Modules TS is now implemented (to various degrees) by GCC, Clang, and MSVC. The aim of this talk is to provide practical information on the mechanics of creating and consuming modules with these compilers. It is based on our experience adding modules support to the build2 toolchain and then modularizing some of its components.

We start with a brief introduction to C++ modules, why we need them, and how they relate to other physical design mechanisms, namely headers, namespaces, and libraries.

Next we explore the kind of integration modules will require from a C++ build system. Specifically, when and where a module binary interface is built? How can a build system discover which modules are needed? What are the implications for parallel and distributed builds? Can we finally get rid of the preprocessor? And what happens to header-only libraries in this brave new modularized world?

With a firm understanding of the implications C++ modules have on the build process, we can try to answer some of the module design questions: What is an appropriate module granularity? Should we have separate module interface and implementation units? Can we have a dual header/module interface for legacy support? Are module-only libraries to become all the rage?

CppCon 2017: Programming with C++ Constraints: Background, Utility, and Gotchas--Walter E. Brown

By Adrien Hamelin | Jul 23, 2018 02:13 PM | Tags: community

Have you registered for CppCon 2018 in September? Registration is open now.

While we wait for this year’s event, we’re featuring videos of some of the 100+ talks from CppCon 2017 for you to enjoy. Here is today’s feature:

Programming with C++ Constraints: Background, Utility, and Gotchas

by Walter E. Brown

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

Compile-time constraints will likely soon become part of our routine C++ programming vocabulary. Why? Such constraints are induced by new core language features (requires-clauses and requires-expressions) that are on the horizon for C++. What are these all about?

Almost every function imposes requirements on its users; violating those requirements typically leads to incorrect programs. Historically, such requirements had to be expressed in comments or other documentation, as there was little machinery to express them in code. Soon we will be able to express more requirements in code, thus allowing compilers to detect and address more violations.

This talk aims to prepare both new and veteran C++ programmers with the necessary background, tutorial information, and advice to exploit this powerful new supplement to function declarations. A case study, illustrating an unexpected gotcha, will conclude the presentation.

C++ Weekly Episode 125: The Optimal Way To Return From A Function—Jason Turner

By Jason Turner | Jul 23, 2018 10:31 AM | Tags: performance efficiency basics

Episode 125 of C++ Weekly.

The Optimal Way To Return From A Function

by Jason Turner

About the show:

In this episode of C++ Weekly Jason investigates the possible methods that one of two string values might be returned from a function. Which option is best? Which option can the compiler optimize the most? Do we take one return path or multiple return paths? Should a ternary be used?