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Overload 149 is now available

By Adrien Hamelin | Feb 25, 2019 12:35 PM | Tags: community

ACCU’s Overload journal of February 2019 is out. It contains the following C++ related articles.

Overload 149 is now available

From the journal:

Rip It Up and Start Again.
Some things can be resurrected, others cannot. Frances Buontempo wonders when we need to repent and start over.

5 Big Fat Reasons Why Mutexes Suck Big Time.
Mutable shared state in multithreaded code is often protected by mutexes. Sergey Ignatchenko reminds us that Re-Actors can avoid many of the problems.

A Small Universe.
Writing a programming language is a hot topic. Deák Ferenc shows us how he wrote a compiler for bytecode callable from C++.

QM Bites: Understand Windows Operating-System Identification Preprocessor Macros.
Quality matters and bite sized articles help. Matthew Wilson returns with a QM Bites.

A Thorough Introduction to Distributed Systems.
What is a distributed system, and why is it so complicated? Stanislav Kozlovski explains.

Don’t Use std::endl.
How do you add a new line in C++? Chris Sharpe suggests std::endl is a tiny utility that’s more trouble than it’s worth.

Cpp On Sea 2019 Trip Report--Arne Mertz

By Adrien Hamelin | Feb 20, 2019 01:12 PM | Tags: community

Were you there?

Cpp On Sea 2019 Trip Report

by Arne Mertz

From the article:

From February 3rd through February 6th I have been in Folkestone, UK, to visit the first C++ On Sea conference.

There must be something in the water on that island that enables them to organize fantastic conferences like ACCUConf and, since this year, C++ On Sea.
C++ On Sea is definitely the best conference I have ever been to, and here’s a little glimpse why I think so...

2 Lines Of Code and 3 C++17 Features - The overload Pattern--Bartlomiej Filipek

By Adrien Hamelin | Feb 18, 2019 11:26 AM | Tags: c++17 advanced

Proof that you can do more!

2 Lines Of Code and 3 C++17 Features - The overload Pattern

by Bartlomiej Filipek

From the article:

While I was doing research for my book and blog posts about C++17 several times I stumbled upon this pattern for visitation of std::variant:

template<class... Ts> struct overload : Ts... { using Ts::operator()...; };
template<class... Ts> overload(Ts...) -> overload<Ts...>;

std::variant<int, float> intFloat { 0.0f };
std::visit(overload(
    [](const int& i) { ... },
    [](const float& f) { ... },
  ),
  intFloat;
);

With the above pattern, you can provide separate lambdas “in-place” for visitation.

It’s just two lines of compact C++ code, but it packs a few interesting concepts.

Let’s see how this thing works and go through the three new C++17 features that enable this one by one.

Why You Should Use std::for_each over Range-based For Loops--Jon Kalb

By Adrien Hamelin | Feb 11, 2019 01:03 PM | Tags: stl intermediate

What do you think?

Why You Should Use std::for_each over Range-based For Loops

by Jon Kalb

From the article:

I’d like start by thanking Jonathan for creating and maintaining the Fluent{C++} blog, for the conversations that it spawns, and for letting me contribute with this guest post. Jonathan has invited me to add my thoughts on his previous posting, Is std::for_each obsolete?

Unit Testing C++ Templates and Mock Injection -- Sumant Tambe

By Sumant | Feb 11, 2019 01:54 AM | Tags: None

Do you unit test your C++ templates? It may be tricky as sometimes it's not clear how to inject mock code into a template. Traits can help! 

Unit Testing C++ Templates and Mock Injection Using Traits

by Sumant Tambe

About the Article:

Unit testing your template code comes up from time to time. (You test your templates, right?) Some templates are easy to test. No others. Sometimes it's not clear how to about injecting mock code into the template code that's under test. I've seen several reasons why code injection becomes challenging.

C++ Links #16—Bartlomiej Filipek and Wojciech Razik

By bfilipek | Jan 29, 2019 12:31 PM | Tags: None

The next episode of the ‘most useful C++ links’ is now available:

C++ Links #16

by Bartlomiej Filipek and Wojciech Razik

From the article:

See the most important and useful articles, podcasts and videos that happen between 19th and 25th of January 2019.

This week you will find a link to a ray-tracer, real-life examples of ranges, new useful features of Microsoft Visual Studio and many more!

Variant Visitation V2--Michael Park

By Adrien Hamelin | Jan 25, 2019 12:42 PM | Tags: performance advanced

Optimising accesses.

Variant Visitation V2

by Michael Park

From the article:

In 2015, I wrote an article titled Variant Visitation which described an implementation strategy for std::visit. The approach involved a matrix of function pointers, and many have raised concerns regarding poor code-gen caused by optimization limitations of function pointers on some compilers.

This post describes the switch-based approach implemented in mpark/variant, and its benchmark results...

C++ moves for people who don’t know or care what rvalues are--Topher Winward

By Adrien Hamelin | Jan 25, 2019 12:33 PM | Tags: intermediate c++11

Is it simpler that way?

C++ moves for people who don’t know or care what rvalues are

by Topher Winward

From the article:

When I was first learning about move semantics in C++, I kept reading articles that explained in terms of other scary sounding jargon — lvalues, rvalue references, memcpy, ownership. None of these things are strictly necessary to know about to understand the core of move semantics. (Though, the more you learn about them, the greater your understanding of move semantics will become.)

You may have heard of move semantics, and may know that they’re “faster”, but not why, or even how to move something. (Here “moves” and “move semantics” mean the same thing.)

This article will deliberately simplify or ignore some concepts (like constructors, rvalue references, stack vs heap) to make the core idea of moving easier to follow, so don’t worry if you already know this stuff and see something that isn’t technically correct. I’ll mark clarifications for these with a number. This article is aimed at those writing everyday (non-library) code, with little to no existing understanding of move semantics, to help get over the initial conceptual hurdle...