Articles & Books

Stop reimplementing the virtual table and start using double dispatch

AndyG wants us to stop misusing dynamic_cast and start using a visitor pattern

Stop reimplementing the virtual table and start using double dispatch

by AndyG

From the article:

In this tutorial, I’ll talk about one solution to this problem I’ve had some success with: the double-dispatch Visitor pattern. With it, you can trim down those long if-else if blocks, separate responsibility into manageable pieces, and even stabilize your interface better.

Exploring C++20 - Class Types in Non-Type Template Parameters—Tobias Widlund

Exciting!

Exploring C++20 - Class Types in Non-Type Template Parameters

by Tobias Widlund

From the article:

If I had to pick out my favourite features planned for C++20, then this one would definitely be amongst the top 5 since I love compile time programming. This feature makes it more natural to write templated code since it allows you to group data together and pass it to a template without having to resort to hacks.

To explain what this feature is about, I will start by talking about normal non-type template parameters from pre-C++20...

The pImpl Idiom—Arne Mertz

In one word.

The pImpl Idiom

by Arne Mertz

From the article:

The pImpl idiom is a useful idiom in C++ to reduce compile-time dependencies. Here is a quick overview of what to keep in mind when we implement and use it...

Don’t pass lambdas (or other multi-line entities) as parameters to macros—Raymond Chen

Not helping you.

Don’t pass lambdas (or other multi-line entities) as parameters to macros

by Raymond Chen

From the article:

Consider this macro:

#ifdef DEBUG
#define LOG(value) LogValue(value)
#else
// In production, evaluate but don't log.
#define LOG(value) (value)
#endif

This seems not entirely unreasonable, but bad things happen if you pass a multi-line entity as the macro parameter...

Move smart pointers in and out functions in modern C++

Different options with different meanings.

Move smart pointers in and out functions in modern C++

by Triangles @ Internal Pointers

From the article:

Passing and returning smart pointers to/from functions are operations that require some planning. There are many ways of doing it and picking the right one is not always straightforward. Luckily for us C++ experts have guidelines that shed some light on this task.

Modern dining philosophers—Lucian Radu Teodorescu

How to solve the dining philosophers problem in 2018? By using tasks. And how to use tasks? Read on...

Modern dining philosophers

by Lucian Radu Teodorescu

From the article:

We give several solutions to the dining philosophers problem, each with some pros and cons. But, more importantly, we walk the reader through the most important aspects of using tasks to solve concurrency problems.

Instead of reaching for our higher-level frameworks, we opted to keep the level of abstractions as close as possible to raw tasks. This way, we hope to guide the reader to understand more about the essence of task-based programming. Our aim is to make the reader comprehend the machinery of composing tasks; those skills should be highly valuable.

The overview of C++20 Range view—Ryou Ezoe

Simple, good.

The overview of C++20 Range view

by Ryou Ezoe

From the article:

The latest C++ draft at the time of writing incorporated The One Ranges Proposal.

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/n4791.pdf

So what is a Range, anyway? The C++ Standard Comittee member, Eric Niebler, summarised it well in this article:

Eric Niebler – Eric Niebler

Actually, he summarised it all too well to the point that his code became almost unreadable to an average C++ programmer. One might say, it's practically useless. So this article serves as a quick tutorial for the Range view...

Quick Q: How to use auto keyword to assign a variable of type uint32_t or uint64_t in C++

Quick A: Write the type!

Recently on SO:

How to use auto keyword to assign a variable of type uint32_t or uint64_t in C++

I'm assuming you're working with the AAA style suggested by Herb Sutter.

In that case, a nice solution is to simply write:

auto variable_name = uint64_t{ 5000000000 };

This is clear, consistent, and explicitly typed with no nasty C-preprocessor necessary.