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Quick Q: Where and why do I have to put the “template” and “typename” keywords?

By Adrien Hamelin | Aug 7, 2019 11:06 AM | Tags: advanced

Quick A: to help the compiler understand what the programmer wants.

Recently on SO:

Where and why do I have to put the “template” and “typename” keywords?

In order to parse a C++ program, the compiler needs to know whether certain names are types or not. The following example demonstrates that:

t * f;

How should this be parsed? For many languages a compiler doesn't need to know the meaning of a name in order to parse and basically know what action a line of code does...

Quick Q: What are copy elision and return value optimization?

By Adrien Hamelin | Aug 5, 2019 12:42 PM | Tags: basics

Quick A: optimisation compilers are allowed to do for perfomance.

Recently on SO:

What are copy elision and return value optimization?

Copy elision is an optimization implemented by most compilers to prevent extra (potentially expensive) copies in certain situations. It makes returning by value or pass-by-value feasible in practice (restrictions apply).

It's the only form of optimization that elides (ha!) the as-if rule - copy elision can be applied even if copying/moving the object has side-effects...

Enabling Polymorphism in SYCL using the C++ idiom "Curiously Recurring Template Pattern"

By rodburns | Aug 1, 2019 11:43 PM | Tags: None

Dynamic polymorphism is a widely used C++ feature that allows code to be more flexible, and helps create easily extendable interfaces by overriding the base class specified interfaces inside our derived classes. However, in SYCL kernel code in order to emulate dynamic polymorphism we need to use some curious tricks and techniques.

Enabling Polymorphism in SYCL using the C++ idiom "Curiously Recurring Template Pattern"

by Georgi Mirazchiyski

From the article:

The CRTP idiom offers an alternative approach to polymorphism by providing us with the ability to specify static interfaces, where the base class specifies the the structure of the interface, while the derived one represents the implementation. In this case, the base class does represent the interface and the derived class represents the implementation — similar to the general idea of polymorphism.

CopperSpice: Inline Namespaces

By Ansel Sermersheim | Aug 1, 2019 11:42 PM | Tags: None

New video on the CopperSpice YouTube Channel:

Inline Namespaces

by Barbara Geller and Ansel Sermersheim

About the video:

In this video, we discuss the purpose of namespaces and the functionality C++11 added with the inline namespace syntax. Join us to find out how inline namespaces can help library developers maintain backward compatibility and how they work.

Please take a look and remember to subscribe!

Comparisons in C++20--Barry Revzin

By Adrien Hamelin | Jul 29, 2019 10:29 AM | Tags: experimental

Get familiar with it, it's coming and it's going to help you!

Comparisons in C++20

by Barry Revzin

From the article:

Now that the Cologne meeting is over and we’ve more or less finalized (at least before the NB comments come in) C++20, I wanted to take the time to describe in detail one of the new language features we can look forward to. The feature is typically referred to as operator<=> (defined in the language as “three-way comparison operator” but more colloquially referred to as “operator spaceship”), but I think it has broader scope than that.

We’re not just getting a new operator, we’re significantly changing the semantics of how comparisons work at a language level...

Trip Report: C++ Standards Meeting in Cologne, July 2019--Botond Ballo

By Adrien Hamelin | Jul 26, 2019 12:51 PM | Tags: community

Lots happened!

Trip Report: C++ Standards Meeting in Cologne, July 2019

by Botond Ballo

From the article:

Last week I attended a meeting of the ISO C++ Standards Committee (also known as WG21) in Cologne, Germany. This was the second committee meeting in 2019; you can find my reports on preceding meetings here (February 2019, Kona) and here (November 2018, San Diego), and previous ones linked from those. These reports, particularly the Kona one, provide useful context for this post...