Quick Q: Compile-time loop optimisation

By Adrien Hamelin | Mar 21, 2019 12:16 PM | Tags: intermediate c++14

Quick A: each release of C++ allows more things to be done at compile time.

Recently on SO:

Compile-time loop optimisation

In C++14, constexpr function requirements were relaxed.

Previously, in C++11, constexpr functions could only contain typedefs, static_asserts and usings, but only a single return statement.

In C++14, it became possible to use loops in constexpr function bodies.

Because b was declared as constexpr char, it must be evaluated at compile time. The compiler then optimised out the isStringNice function, as it is not used at run time.

Game performance and compilation time improvements in Visual Studio 2019--Gratian Lup

By Adrien Hamelin | Mar 21, 2019 12:03 PM | Tags: performance community

Getting better!

Game performance and compilation time improvements in Visual Studio 2019

by Gratian Lup

From the article:

The C++ compiler in Visual Studio 2019 includes several new optimizations and improvements geared towards increasing the performance of games and making game developers more productive by reducing the compilation time of large projects. Although the focus of this blog post is on the game industry, these improvements apply to most C++ applications and C++ developers...

How do I design a class so that methods must be called in a certain order?--Raymond Chen

By Adrien Hamelin | Mar 20, 2019 12:39 PM | Tags: None

Simple but effective.

How do I design a class so that methods must be called in a certain order?

by Raymond Chen

From the article:

Suppose you have a class with some methods, and the methods must be called in a certain order. For example, suppose your class is for importing photos from a camera. First, you have to specify which camera you are importing from. Then you discover the pictures. Then you have to select which pictures you want to import, and set the options for how you want the download to occur. And finally, you download them...

C++ Insights - Implicit Conversions--Andreas Fertig

By Adrien Hamelin | Mar 20, 2019 12:25 PM | Tags: intermediate community

A good tool!

C++ Insights - Implicit Conversions

by Andreas Fertig

From the article:

This series is motivated by a brief conversation I had with Andreas. I asked him if he has some use case examples which show how C++ Insights can be helpful when teaching. I think there are many things. This article is the start of a series of five posts by Andreas which I will publish at Modernes C++ because I think C++ Insights is an invaluable tool to get a deeper insight in the C++ compiler magic. In case, you are new to C++ Insights consider this introductory article. Without further ado, Andreas post. When you follow the link near to each example, you can directly analyse the example in C++ Insight...

Quick Q: Deletion of copy-ctor & copy-assignment - public, private or protected?

By Adrien Hamelin | Mar 20, 2019 12:21 PM | Tags: intermediate c++11

Quick A: The meaning is the same for the compiler, so chooses what make sense to you.

Recently on SO:

Deletion of copy-ctor & copy-assignment - public, private or protected?

I would put them in the public section.

This is because deleting a constructor or an assignment operator is orthogonal to making them private / protected; and when these aren't deleted, they are public. Putting the deletions in one of those two sections seems to me like hinting "If I hadn't deleted them, I would have made them private/protected" - which is not a message you want to convey in your case.

Note, though, that the compiler doesn't care which section you put the deletion in.

Macro Evil in C++ Code

By Andrey Karpov | Mar 20, 2019 10:53 AM | Tags: macros bugs

The C++ language opens extensive opportunities to go without macros. So let’s try to use macros as seldom as possible!

Macro Evil in C++ Code

by Andrey Karpov

From the article:

The ATL library provides such macros, as A2W, T2W and so on for string conversion. However, few people know that it is very dangerous to use these macros inside loops. Within the macro, a call to the alloca function occurs, which will repeatedly allocate memory on each loop iteration on the stack. A program makes show that it works correctly. Once a program starts to handle longer strings and the number of loop iterations increases, the stack can just end at the most unexpected moment.

2019-03 post-Kona mailing available

By Blog Staff | Mar 19, 2019 04:18 PM | Tags: None

The 2019-03 mailing of new standards papers is now available.

Interview with Bjarne Stroustrup invested Doctor Honoris Causa at University Carlos III of Madrid

By jdgarcia | Mar 19, 2019 12:21 PM | Tags: None

On January 25th 2019, Bjarne Stroustrup was invested as Doctor Honoris Causa at University Carlos III of Madrid (Spain).

Honorary Doctorates are the highest honor that a Spanish Univeristy gives to somebody for their merit in the academic, scientific or artistic fields of activity.

Interview with Bjarne Stroustup

by Daniel Garcia

About the interview

In this short interview Dr. Stroustrup talks about the C++ programming language, the reasons that lead to its inception, its impact and other related topics.

Template meta-functions for detecting template instantiation--Ivan Čukić

By Adrien Hamelin | Mar 19, 2019 11:44 AM | Tags: c++17 advanced

Templates are great.

Template meta-functions for detecting template instantiation

by Ivan Čukić

From the article:

I’ve been playing around with type meta-tagging for my Voy reactive streams library (more on that some other time) and realized how useful it is to be able to check whether a given type is an instantiation of some class template, so I decided to write a short post about it...

Quick Q: What is a lambda expression in C++11?

By Adrien Hamelin | Mar 19, 2019 11:42 AM | Tags: c++11 basics

Quick A: A convenient way to create a functor.

Recently on SO:

What is a lambda expression in C++11?

C++ includes useful generic functions like std::for_each and std::transform, which can be very handy. Unfortunately they can also be quite cumbersome to use, particularly if the functor you would like to apply is unique to the particular function.

#include <algorithm>
#include <vector>

namespace {
  struct f {
    void operator()(int) {
      // do something
    }
  };
}

void func(std::vector<int>& v) {
  f f;
  std::for_each(v.begin(), v.end(), f);
}

If you only use f once and in that specific place it seems overkill to be writing a whole class just to do something trivial and one off...