Create a new type when using std::variant -- Zhihao Yuan

By Zhihao Yuan | Nov 24, 2020 10:45 AM | Tags: None

Enough typedefs.

Create a new type when using std::variant

by Zhihao Yuan

From the article:

class rock {};
class paper {};
class scissors {};
using hand = std::variant<rock, paper, scissors>;

Ignoring the fact that this hand type comes with heavily overloaded constructors and you can only add free functions, a troublesome issue is that the type-name std::variant<rock, paper, scissors> will appear everywhere in debuggers and linkers in place of hand.

Conditionally Trivial Special Member Functions--Sy Brand

By Adrien Hamelin | Nov 23, 2020 11:47 AM | Tags: c++20 c++17

c++ magic.

Conditionally Trivial Special Member Functions

by Sy Brand

From the article:

The C++ standards committee is currently focusing on adding features to the language which can simplify code. One small example of this in C++20 is conditionally trivial special member functions, which we added support for in Visual Studio 2019 version 16.8. Its benefit isn’t immediately obvious unless you’ve been deep down the rabbit hole of high-performance library authoring, so I’ve written this post to show you how it can make certain generic types more efficient without requiring huge amounts of template magic...

How to Share Code with Const and Non-Const Functions in C++--Bartlomiej Filipek

By Adrien Hamelin | Nov 23, 2020 11:41 AM | Tags: intermediate

How do you do it?

How to Share Code with Const and Non-Const Functions in C++

by Bartlomiej Filipek

From the article:

During the development of a container-like type, I run into the problem of how to share code between a const and non-const member functions. In this article, I’d like to explain what are the issues and possible solutions. We can even go on a bleeding edge and apply some C++20 features. Which technique is most friendly?

Calendar and Time-Zones in C++20: Time-Zones--Rainer Grimm

By Adrien Hamelin | Nov 23, 2020 11:40 AM | Tags: c++20

Time computations.

Calendar and Time-Zones in C++20: Time-Zones

by Rainer Grimm

From the article:

This post concludes my introduction to the chrono extension in C++20. Today I present the time-zones functionality.

2020-11 mailing available

By Administrator | Nov 22, 2020 11:20 AM | Tags: None

The 2020-11 mailing of new standards papers is now available.

Why PVS-Studio Doesn't Offer Automatic Fixes

By Andrey Karpov | Nov 19, 2020 01:13 AM | Tags: static code analysis pvs-studio bugs

Static analyzer PVS-Studio can detect bugs in pretty complex and intricate parts of code, and coming up with appropriate fixes for such bugs may be a tough task even for human developers. That's exactly the reason why we should avoid offering any options for automatic fixing at all. Here are a couple of examples.

Why PVS-Studio Doesn't Offer Automatic Fixes

by Andrey Karpov

From the article:

But it only simplifies the code, not fixes it! Somebody else noticed this and opened a discussion: os_thread_windows.c - get_rel_wait() will block if abstime is in the past. As you can see, even humans make mistakes when trying to come up with a fix. Machines are just hopeless in that respect.

Overload 159 is now available

By Adrien Hamelin | Nov 16, 2020 11:57 AM | Tags: community

ACCU’s Overload journal of October 2020 is out. It contains the following C++ related articles.

Overload 159 is now available

From the journal:

Virtual/Reality
By Frances Buontempo
Do we know what reality is? Frances Buontempo is no longer sure and now wonders if she’s a fictional character.

poly::vector – A Vector for Polymorphic Objects
By Ferenc Nándor Janky
Heterogeneous vectors can be slow. Janky Ferenc introduces a sequential container for storing polymorphic objects in C++.

Kafka Acks Explained
By Slanislav Kozlovski
Kafka’s configuration can be confusing. Slanislav Kozlovski helps us visualise this most misunderstood configuration setting.

Concurrency Design Patterns
By Lucian Tadu Teodorescu
Orchestrating concurrent tasks using mutexes is seldom efficient. Lucian Tadu Teodorescu investigates design patterns that help unlock concurrent performance.

C++ Modules: A Brief Tour
By Nathan Sidwell
C++20’s long awaited module system has arrived. Nathan Sidwell presents a tourist’s guide.

The Edge of C++
By Ferenc Deák
Everything has limits. Deák Ferenc explores the bounds of various C++ constructs.

Afterwood
By Chris Oldwood
Assume failure by default. Chris Oldwood considers various fail cases.

Destructing outside the lock when removing items from C++ standard containers--Raymond Chen

By Adrien Hamelin | Nov 16, 2020 11:55 AM | Tags: advanced

How do you do it?

Destructing outside the lock when removing items from C++ standard containers

by Raymond Chen

From the article:

Last time, we saw that object destruction is a hidden callout that can cause you to violate the rule against calling out to external code while holding an internal lock...

Quick Q: Why do I have to access template base class members through the this pointer?

By Adrien Hamelin | Nov 16, 2020 11:45 AM | Tags: advanced

Quick: in order to make x a dependent name, so that lookup is deferred until the template parameter is known

Recently on SO:

Why do I have to access template base class members through the this pointer?

If the classes below were not templates I could simply have x in the derived class. However, with the code below, I have to use this->x. Why?

template <typename T>
class base {

protected:
    int x;
};

template <typename T>
class derived : public base<T> {

public:
    int f() { return this->x; }
};

int main() {
    derived<int> d;
    d.f();
    return 0;
}

Dependency Injection with Boost.DI -- Richard Thomson

By Legalize Adulthood | Nov 16, 2020 11:07 AM | Tags: None

Utah C++ Programmers has released a video on dependency injection with the Boost.DI library.

Dependency Injection with Boost.DI

by Richard Thomson

From the video description:

Richard Thomson gives us a presentation on dependency injection in C++.  We'll look at dependency injection in general and then look at dependency injection using the Boost.DI library.

YouTube: https://www.youtube.com/watch?v=zMTAc8WHIgo