In a previous blog post we introduced clazy, a clang plugin which makes the compiler understand Qt semantics, allowing you to get compile-time warnings about Qt best practices ranging from unneeded memory allocations to misuse of API, including fix-its for automatic refactoring. Today we'll do a round-up and present the checks related to connect statements, […]

A small new feature that I have added to Qt 5.8 is the possibility of disabling narrowing conversions in the new-style QObject::connect statement. In this short blog post I would like to share with you why I thought this was useful and therefore implemented it. The problem Since Qt 5.0, the new-style, PMF-based (pointer to […]

After two months of intensive reviews, discussions, fixes, and stripping down the initial commit, feature by feature, to make it acceptable, I am happy to announce that the first QStringView commits have landed in what will eventually become Qt 5.10. Even the docs are already on-line. This is a good time to briefly recapitulate what […]

This blog series will introduce the clang-tidy utility from the Clang/LLVM project and show how to use it to automatically refactor C++ source code and integrate with your build system, as well as how to use the tool on other platforms than Unices. Motivation: The joy of legacy code bases C++11 added a significant amount […]

All Qt developers have asked themselves at least once in their careers: "why isn't my slot invoked?" (I've asked myself that question many, many times). There are a number of reasons why a connection may fail to be properly set up, and ultimately cause our slot not to be invoked. This blog post is a […]

A small new feature that was added to Qt 5.8 is the ability for moc (Qt's meta-object compiler) to extract meta-object information at the namespace level. This means, for instance, that you can have introspection support for enumerations defined in a namespace (not just in QObject subclasses, or classes tagged with Q_GADGET), and use such […]

I'm extremely happy to finally announce the first stable release of heaptrack, the FOSS heap memory profiler for C/C++ Linux applications. You can download the source tarball from the KDE mirrors: https://download.kde.org/stable/heaptrack/1.0.0/src/ Heaptrack is a fast heap memory profiler that runs on Linux. It allows you to track all heap memory allocations at run-time. Afterwards, […]

Qt 5.8 has just been released! Another great release of Qt, made possible by thousands of commits by over a hundred different contributors: And here we are again, with the usual showcase of the most outstanding contributions to Qt 5.8 developed by KDAB engineers. In no particular order: Qt 3D Qt 3D continues to receive […]

Knowing what tools are at your disposal when looking to make a program faster or keep it operating smoothly is critical to your success as a programmer. We recently solved a performance problem using Linux Kernel Tracepoints so we thought we’d share the process with you so that you can see for yourself if this […]

In the last blog post we gave a very high level introduction to the Qt Quick 2 renderer. We also showed how various signals are emitted by the renderer during the synchronization and rendering steps. In this blog post we're going to discuss those signals and show how they can be used to implement overlays […]

This is the first in a series of blog posts on QStringView, the std::u16string_view equivalent for Qt. You can read about QStringView in my original post to the Qt development mailing-list, follow its status by tracking the "qstringview" topic on Gerrit and learn about string views in general in Marshall Clow's CppCon 2015 talk, aptly […]

In the last days, I was once again trying to convince fellow programmers that there's no such thing as a "benign" data race. This is a recurring theme, in particular fueled by the docs of MSVC and Intel x86, which basically seem to say "you don't need atomics here". I perused the excellent papers Benign […]

The last post from my colleague Marc Mutz about deprecating Q_FOREACH caused quite an uproar amongst the Qt developers who follow this blog. I personally feel that this was caused fundamentally by a perceived threat: there is a cost associated to porting away a codebase from a well-known construct (Q_FOREACH) to a new and yet-undiscovered […]

In this article, I will take a look at one of the fundamental concepts introduced in Alex Stepanov and Paul McJones’ seminal book "Elements of Programming" (EoP for short) — that of a (Semi-)Regular Type and Partially-Formed State. Using these, I shall try to derive rules for C++ implementations of what are commonly called "value […]

Functional Safety is the term used for systems designed to minimize risk to human health. But there’s a dilemma in today’s tech-driven world. We are more reliant than ever on software to control our planes, trains, cars, and boats, to operate our medical equipment, to process our food, to clean our water, and to power […]

For today's blog I would like to share with you the little adventure I had when fixing a very strange bug in Qt. Pop quiz Don't think about this too much, just guess: what does this QML snippet print? There are no JavaScript semantic tricks involved; and using either == or === does not change […]

Are you a Qt developer and do you use Linux as your development platform of choice? Then this talk is for you: I will introduce you to perf, the Linux tool suite for performance analysis. The talk will not only cover a broad part of what perf has to offer, it will also dive into […]

A retrospective on the KDE community from 20 years ago and how things were done back then, with an emphasis on community spirit and fun facts. Over time, the KDE community has seen many people join and leave, as with any open source community, which means that very few people in the current community still […]

The past year was very important for the KDE PIM community. We released the first Qt5-based version, restructured our code base and set ourselves more ambitious goals. Let's look a bit deeper into some of the important changes that have happened in KDE PIM in the past year, and peak a little into the future. […]

Many KDAB engineers are part of the Qt Security Team. The purpose of this team is to get notified of security-related issues, and then decide the best course of action for the Qt project. Most of the time, this implies identifying the problem, creating and submitting a patch through the usual Qt contribution process, waiting […]