CppCon 2019 Trip Report and Slides

by Anthony Williams

Having been back from CppCon 2019 for over a week, I thought it was about time I wrote up my trip report...

C++ Core Guidelines: Bounds Safety

by Rainer Grimm

Today's post is about the second profile of the C++ Core Guidelines: Bounds Safety. The goal of the profile bounds safety is it that you operate inside the bounds of allocated memory...

Alternatives to C++ Function Pointers in SYCL using Function Objects

by Georgi Mirazchiyski

Function Pointers are a feature of the C language and so form part of the C++ standard. As such, a function pointer allows the following behavior:

    "A pointer to a function can be passed as a parameter to another function"

In C++, especially in modern C++, function pointers are a legacy feature from the C language but they still exist in some code bases.

SYCL enables single source development where template functions can contain both host and device code to construct complex algorithms that use acceleration. However, SYCL does not provide support for function pointers since this is a limitation posed by the design of OpenCL v1.2 which is the basis of the current SYCL v1.2.1 definition.

But there is good news, we can use modern C++ to implement a solution that can be used with SYCL. SYCL is built with C++11 (and onward depending on the implementation), meaning features like anonymous functions known as "lambdas" can be used with little to zero overhead. Even going back to C++98/03 it is possible to use function objects defined as either structs or classes, and additionally, you can template your operation (the computation logic) to provide a generic way to consume the function objects or lambdas.

String literals make bad ranges

by Andrzej Krzemieński

C++20 will come with what we call “Ranges” library. Meanwhile, range interface has been supported ever since C++11 in one context: range-based for loop. A range-based for loop can detect anything that is a range and work with it. In particular, it can work with string literals...

C++ Tricks: Fast RTTI and Dynamic Cast

by Samuel Kahn

As introduced in the first post of these series, I will share the first piece of KCL: an implementation of RTTI and Dynamic Cast. The code can be found on GitHub.

If you don’t know what dynamic casting is, then I suggest you read some online resources before diving into this article...

Expressive Code for State Machines in C++

by Valentin Tolmer

Have you ever run into this kind of comments?

// IMPORTANT: Do not call this function before calling SetUp()!

Or checks like these:

if (my_field_.empty()) abort();

Those are all symptoms of a (often light-weight) protocol that our code must respect. Or sometimes, you have an explicit protocol that you’re following, such as in the implementation of an SSL handshake or other business logic. Or maybe you have an explicit state machine in your code, with the transitions checked each time against a list of possible transitions.

Let’s have a look at how we can expressively handle these cases...

C++ Core Guidelines: Type Safety by Design

by Rainer Grimm

What does that mean: type safety by design. Type safety by design just means, that you always initialise your variables, use std::variant instead of a union, or prefer variadic templates and fold expressions to va_arg's...

How C++ ‘using’ or alias-declaration is better than typedef

by nextptr

Alias-declaration or type-alias with 'using' statement offers a more flexible way to define type aliases than typedef, mainly because of alias templates...

C++ Russia 2019

Two days, three tracks and dozens of in-depth technical talks about C++: concurrency, performance, architecture, environment — all you need to make your code perfect.

Keynote by Sean Parent, Eric Niebler and Ivan Čukić.

Also at the conference: Marshall Clow, Björn Fahller, Maxim Khizhinsky, Hana Dusíková, Rainer Grimm and many others.

C++ Russia is not only the talks but also networking with hundreds of colleagues from Russia and Europe. Due to dedicated discussion zones, all the speakers have after their talks, all the questions will be answered.

And in the evening you can participate in BoF-sessions where the most uncommon ideas are born.
Fourteen talks will be entirely in English.

De-fragmenting C++: Making Exceptions and RTTI More Affordable and Usable

by Herb Sutter

A fundamental reason why C++ is successful and loved is its adherence to Stroustrup’s zero-overhead principle: You don’t pay for what you don’t use, and if you do use a feature you can’t reasonably code it better by hand. In the C++ language itself, there are only two features that violate the zero-overhead principle, exception handling and RTTI – and, unsurprisingly, these are also the only two C++ language features that every C++ compiler has switches to turn off and that are regularly discouraged or even banned. This matters because not using these features is the largest current cause of fragmentation of the C++ community into incompatible dialects, and the cause of recurring problems including type confusion security vulnerabilities arising from “didn’t down-cast using dynamic_cast because that would be too slow.” This talk is about ongoing long-term efforts to try to unify the community in this area, not by replacing exceptions and RTTI, but by doubling down: fully embracing exceptions and RTTI, and improving them so they can be zero-overhead too.