Deducing your intentions--Andrzej Krzemieński

By Adrien Hamelin | Dec 12, 2018 08:29 AM | Tags: c++17 advanced

Were you aware?

Deducing your intentions

by Andrzej Krzemieński

From the article:

The language feature in C++17 known as class template argument deduction was intended to supersede factory functions like make_pair, make_tuple, make_optional, as described in p0091r2. This goal has not been fully achieved and we may still need to stick to make_ functions. In this post we will briefly describe what class template argument deduction is, and why it works differently than what people often expect...

Standard Ranges--Eric Niebler

By Adrien Hamelin | Dec 10, 2018 09:36 AM | Tags: experimental

Coming soon.

Standard Ranges

by Eric Niebler

From the article:

As you may have heard by now, Ranges got merged and will be part of C++20. This is huge news and represents probably the biggest shift the Standard Library has seen since it was first standardized way back in 1998.

This has been a long time coming. Personally, I’ve been working toward this since at least November 2013, when I opined, “In my opinion, it’s time for a range library for the modern world,” in a blog post on input ranges. Since then, I’ve been busy building that modern range library and nailing down its specification with the help of some very talented people.

Future blog posts will discuss how we got here and the gritty details of how the old stuff and the new stuff play together (we’re C++ programmers, we love gritty details), but this post is strictly about the what...

span: the best span--Barry Revzin

By Adrien Hamelin | Dec 10, 2018 09:27 AM | Tags: experimental

An answer.

span: the best span

by Barry Revzin

From the article:

This post is a response to RangeOf: A better span, which has many problems worth addressing in detail. While most of this post will deal with specifically std::span<T> (which is indeed the best span), the last section will also discuss a recent addition to the standard library: std::ranges::subrange<T*>...

SG20 Education and Recommended Videos for Teaching C++ -- Christopher Di Bella

By Christopher Di Bella | Dec 9, 2018 10:21 AM | Tags: None

In today’s blog, we look at both the newly minted Study Group for education in the C++ Standard Committee. We also look at a small number of conference videos that I recommend teachers consider while they’re waiting for this Study Group to produce usable materials.

SG20 Education and Recommended Videos for Teaching C++

by Christopher Di Bella

From the article:

As articulated in P1231, the goal of SG20 is not to provide normative curricula for teaching C++, but rather to provide teaching and curriculum guidelines.

...

Below are a list of conference videos that I’ve compiled for teachers to watch (and will update if recommendations come in). There’s well over a day’s worth of videos below, but these aren’t a random assortment of my favourite conference videos. Rather, they are sessions that communicate values about:

• teaching people how to write programs using C++, or
• writing C++ programs using approaches the community agrees produce better code.

An Extraterrestrial Guide to C++ Formatting--Victor Zverovich

By Adrien Hamelin | Dec 6, 2018 01:45 PM | Tags: None

The future of now.

An Extraterrestrial Guide to C++ Formatting

by Victor Zverovich

From the article:

Consider the following use case: you are developing the Enteropia[2]-first Sepulka[3]-as-a-Service (SaaS) platform and have a server code written in C++ that checks the value of sepulka’s squishiness received over the wire and, if the value is invalid, logs it and returns an error to the client. Squishiness is passed as a single byte and you want to format it as a 2-digit hexadecimal integer, because that is, of course, the Ardrite[1] National Standards Institute (ANSI) standard representation of squishiness. Let’s implement the logging part using different formatting facilities provided by C++...

Quick Q: Is it useful to pass std::weak_ptr to functions?

By Adrien Hamelin | Dec 6, 2018 01:42 PM | Tags: None

Quick A: yes

Recently on SO:

Is it useful to pass std::weak_ptr to functions?

Consider this toy example.

struct PointerObserver
{
    std::weak_ptr<int> held_pointer;

    void observe( std::weak_ptr<int> p )
    {
        held_pointer = std::move(p);
    }

    void report() const
    {
        if ( auto sp = held_pointer.lock() )
        {
            std::cout << "Pointer points to " << *sp << "\n";
        }
        else
        {
            std::cout << "Pointer has expired.\n";
        }
    }
};

In this example, a function observe holds state.

Its weak_ptr parameter communicates that this smart pointer is not owning, but reserves the ability to own at a later time, safely detecting if the pointer has expired.

How to Use The Newest C++ String Conversion Routines - std::from_chars--Bartlomiej Filipek

By Adrien Hamelin | Dec 6, 2018 01:37 PM | Tags: intermediate c++17

Still learning about C++17.

How to Use The Newest C++ String Conversion Routines - std::from_chars

by Bartlomiej Filipek

From the article:

With C++17 we get another facility to handle the conversion between text and numbers. Why should we care about the new routines? Are they better in any way?

Quick Q: Is there std::memset equivalent for std::array?

By Adrien Hamelin | Dec 5, 2018 02:26 PM | Tags: intermediate

Quick A: the fill() function.

Recently on SO:

Is there std::memset equivalent for std::array?

Use the array's fill() method, that is what its purpose is.

If you fill it with 0 (for integers, for instance), then the compiler may optimize it if it can (often does, you can look at the generated code).

How to optimize C and C++ code in 2018--Iurii Krasnoshchok

By Adrien Hamelin | Dec 5, 2018 01:00 PM | Tags: performance advanced

Are you aware?

How to optimize C and C++ code in 2018

by Iurii Krasnoshchok

From the article:

We are still limited by our current hardware. There are numerous areas where it just not good enough: neural networks and virtual reality to name a few. There are plenty of devices where battery life is crucial, and we must count every single CPU tick. Even when we’re talking about clouds and microservices and lambdas, there are enormous data centers that consume vast amounts of electricity.

Even boring tests routine may quietly start to take 5 hours to run. And this is tricky. Program performance doesn‘t matter, only until it does.

A modern way to squeeze performance out of silicon is to make hardware more and more sophisticated...

Trip Report: C++ Standards Meeting in San Diego, November 2018--Botond Ballo

By Adrien Hamelin | Dec 5, 2018 12:58 PM | Tags: experimental community

New trip report.

Trip Report: C++ Standards Meeting in San Diego, November 2018

by Botond Ballo

From the article:

A few weeks ago I attended a meeting of the ISO C++ Standards Committee (also known as WG21) in San Diego, California. This was the third committee meeting in 2018; you can find my reports on preceding meetings here (June 2018, Rapperswil) and here (March 2018, Jacksonville), and earlier ones linked from those. These reports, particularly the Rapperswil one, provide useful context for this post...