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CppCon 2017: Building C++ Modules—Boris Kolpackov

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?

C++/CLI support comes to ReSharper C++

Two big worlds of C++ and C# are bridged by the interop language, C++/CLI, and now it's supported in ReSharper C++, a Visual Studio extension from JetBrains.

C++/CLI support comes to ReSharper C++

by Phil Nash

From the article:

While C# is a highly productive language, and is no slouch when it comes to performance, there are many reasons that we may also have a parts of our project written in pure C++. C++/CLI is an answer to the question, “how do I get to, or from, my pure C++ from C# (or any .NET language)?”. If you just need to call into C++, and it exposes a C API, P/Invoke may be the simplest way to go. But for more complex cases – where you want to model richer types and class hierarchies – C++/CLI let’s you do that.

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

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.

Announcing “trivially relocatable”—Arthur O’Dwyer

Do you want this?

Announcing “trivially relocatable”

by Arthur O’Dwyer

From the article:

Frequent users of Compiler Explorer, a.k.a. godbolt.org, may have noticed that a few days ago a new compiler appeared in its dropdown menu. “x86-64 clang (experimental P1144)” is a branch of Clang which I have patched to support the concept of “trivially relocatable types,” as described in my C++Now 2018 talk and as proposed for standardization in my upcoming paper P1144 “Object relocation in terms of move plus destroy” (coauthored with Mingxin Wang)...

How to Construct C++ Objects Without Making Copies—Miguel Raggi

Avoiding copies.

How to Construct C++ Objects Without Making Copies

by Miguel Raggi

From the article:

C++ references are a powerful but tricky tool: used correctly, they can improve performance with little impact on the clarity of code. But used badly, they can hide performance issues, or even send a peaceful program into the realm of undefined behaviour.

In this post, we will explore how to use the various references of C++ to minimize copies when constructing an object that holds a value, and how in some cases we can even reach zero copies.

This article assumes that you’re familiar with move semantics, lvalue, rvalue and forwarding references. If you’d like to be refreshed on the subject, you can take a look at lvalues, rvalues and their references.

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

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?

Customisation points to support interfaces—Krzysztof Ostrowski

Testable interfaces with polymorphic backends.

Customisation points to support interfaces

by Krzysztof Ostrowski

From the article:

Definition of an interface is not a trivial task. The resulting abstraction that embeds the defined interface actions does not have to be a set of virtual member functions wrapped into a class from which implementations exposed to the user derive. General guideline promoted in this article is to expose non-virtual interfaces to the user while providing a customisation point in the form of a minimal set of actions that can be combined with each other.

CppCast Episode 159: Design Patterns in Modern C++ with Dmitri Nesteruk

Episode 159 of CppCast the only podcast for C++ developers by C++ developers. In this episode Rob and Jason are joined by Dmitri Nesteruk to discuss Design Patterns with Modern C++.

CppCast Episode 159: Design Patterns in Modern C++ with Dmitri Nesteruk

by Rob Irving and Jason Turner

About the interviewee:

Dmitri Nesteruk is a quantitative analyst, developer, course and book author, and an occasional conference speaker. His interests lie in software development and integration practices in the areas of computation, quantitative finance and algorithmic trading. His technological interests include C# and C++ programming as well high-performance computing using technologies such as CUDA and FPGAs.

CppCon 2017: Undefined Behaviour is awesome!—Piotr Padlewski

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:

Undefined Behaviour is awesome!

by Piotr Padlewski

(watch on YouTube) (watch on Channel 9)

Summary of the talk:

Undefined behavior (UB) is one of the features of C++ that is both loved and hated. Every C++ developer cares about performance, which is why it is very important to understand what the compiler can optimize and what are the language guarantees. Many times programmers are too optimistic about what the compiler can optimize, or they waste time optimizing code by hand.

In this talk you will learn:
- what is the “as-if” rule
- why compilers know less than the programmer — the main problem with Translation Units
- why compilers optimize based on UB, but don't warn about it
- why Undefined Behavior can transcend time, removing your whole code without running 88mph
- why having a more constrained language is better — optimizations that you can’t do in C