News

Overload 137 is now available

ACCU’s Overload journal of February 2017 is out. It contains the following C++ related articles.

Overload 137 is now available

From the journal:

Mean Properties
Property based testing is all the rage. Russel Winder walks us through an example of properties an arithmetic mean function should have. by Russel Winder

The Importance of Back-of-Envelope Estimates
Guestimate questions make many people grumble. Sergey Ignatchenko reminds us why they matter. by Sergey Ignatchenko

Multiprocessing and Clusters in Python
Multiprocessing is possible in Python. Silas S. Brown shows us various ways. by Silas S. Brown

doctest – the Lightest C++ Unit Testing Framewor
C++ has many unit testing frameworks. Viktor Kirilov introduces doctest. by Viktor Kirilov

Correct Integer Operations with Minimal Runtime Penalties
Results of C++ integer operations are not guaranteed to be arithmetically correct. Robert Ramey introduces a library to enforce correct behaviour. by Robert Ramey

Quick Q: why there is no data-race in the following case?

Quick A: No write is triggered so no data race occurs.

Recently on SO:

why there is no data-race in the following case?

Data races are not static properties of your code. They are properties of the actual state of the program at execution time. So while that program could be in a state where the code would produce a data race, that's not the question.

The question is, given the state of the system, will the code cause a data race? And since the program is in a state such that neither thread will write to either variable, then the code will not cause a data race.

Data races aren't about what your code might do. It's about what they will do. Just as a function that takes a pointer isn't undefined behavior just because it uses the pointer without checking for NULL. It is only UB if someone passes a pointer that really is NULL.

C++ Weekly Episode 50: Inheriting Lambdas vs Generic Lambdas—Jason Turner

Episode 50 of C++ Weekly.

Inheriting Lambdas vs Generic Lambdas

by Jason Turner

About the show:

The last episode of C++ Weekly showed why and where we might want to inherit from lambdas and create a merged lambda with the signatures of two or more other lambdas. In this episode Jason compares a merged lambda with a generic lambda and what the pros and cons might be.

CppCast Episode 88: Microsoft's STL with Stephan T. Lavavej

Episode 88 of CppCast the only podcast for C++ developers by C++ developers. In this episode Rob and Jason are joined by Stephan T. Lavavej to talk about Microsoft's STL and some of the changes to the Library coming in the VS 2017 release.

CppCast Episode 88: Microsoft's STL with Stephan T. Lavavej

by Rob Irving and Jason Turner

About the interviewee:

Stephan T. Lavavej is a Principal Software Engineer at Microsoft, maintaining Visual C++'s implementation of the C++ Standard Library since 2007. He also designed a couple of C++14 features: make_unique and the transparent operator functors. He likes his initials (which people can actually spell) and cats (although he doesn't own any).

Using QtCreator together with the Visual Studio Build Tools

A first posting about working with Qt and Visual C++ in QtCreator

Using QtCreator together with the Visual Studio Build Tools

by Jens Weller

From the article:

For a while I've been using QtCreator as my IDE, mostly because its deep integration with Qt, as most of my projects are Qt related. With this, I also preferred (and still do a little) to use the MinGW builds of Qt on Windows. In the past, as GCC was a little bit better with the newer standards, today, well, never change a running system...

Dependencies in the Gang of Four examples -- Zebedee Mason

Zebedee Mason discusses in his recent article some GOF idioms and analyzes them with his tool DeepsEnds.

Dependencies in the Gang of Four examples

by Zebedee Mason

From the article:

The example C++ code from the GoF (Gang of Four) book Design Patterns has had its dependencies analysed with DeepEnds. Certain examples have been refactored to remove circular dependencies enabled by pre-declaration of classes. These cycles in the graph serve to reduce the ability to subsequently modify the code with ease.

Fold Expressions--Rainer Grimm

Do you know how they work?

Fold Expressions

by Rainer Grimm

From the article:

With fold expressions you can implement the from Haskell known functions foldl, foldr, foldl1 and foldr1 directly in C++. These four functions successively reduce a list to a single value...

Un-Deprecate Your Qt Project--Giuseppe D'Angelo

Giuseppe D'Angelo explains how the Qt project deprecates APIs, a challenge every library project faces.

Un-Deprecate Your Qt Project

by Giuseppe D'Angelo

From the article:

Any product needs to evolve if it wants to remain competitive. If the development bandwidth is finite, from time to time there is the need to drop some ballast. This does not necessarily mean dropping working functionality and leaving users in the cold. At least in Qt most of the time this actually means replacing working functionality with better working functionality.

This process has being going on in Qt since forever, but since Qt 5.0 we’ve started to formalize it in terms of documentation hints and macros in the source code. This was done with a precise purpose: we wanted Qt users to discover if they were using deprecated APIs, and if so, let them know what better alternatives were available.

And since the very release of Qt 5.0.0 we’ve officially deprecated hundreds of APIs: a quick grep in QtBase alone reveals over 230 hits (mostly functions, but also entire classes).