17.04.2020 
Qt has a long history. The first stable version was released before the first version of C++ was standardized and long before the different C++ compiler vendors started shipping usable implementations of the C++ standard library. Because of this, Qt often followed (and still follows) some design idioms that feel unnatural to the usual C++ […]
Blog Archives
Getting rid of “volatile” in (some of) Qt
The upcoming version of the C++ Standard (C++2a) is proposing to deprecate certain usages of the volatile keyword, by adopting the P1152 proposal (Deprecating volatile). Despite the somewhat “flamboyant” title, the actual deprecated parts are very limited and indeed the paper limits the deprecation to somehow language/library corner cases and/or dangerous antipatterns. For instance certain […]
An Unexpected C++ Journey Can you use Umlaut in variable names?
Some of you may know that KDAB employees enjoy flexibility on working hours as well as location, and some choose to work from home, with the opportunity to share childcare, do part-time study or simply enjoy an out-of-the-way location. All that’s required is a decent bandwidth for KDAB work. About once a year, all of […]
QStringView Diaries: The Eagle Has Landed QStringView merged for Qt 5.10
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 […]
Clang-Tidy, part 1: Modernize your source code using C++11/C++14 Automated refactoring of your source code using powerful open-source tooling
This blog series will introduce the clang-tidy utility from the Clang/LLVM project and show how to use it to automatically refactor
New in Qt 5.8: meta-object support for namespaces Using namespaces in Qt for enumeration introspection
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 […]
Un-deprecate your Qt project
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 […]
Stepanov-Regularity and Partially-Formed Objects vs. C++ Value Types
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 […]
Tuple And Pair in C++ APIs? A Simple Design Goal to Improve Your C++ APIs
Quick: When you design C++ APIs, when and how should you use pair and tuple? The answer is as simple as it is surprising: Never. Ever. When we design APIs, we naturally strive for qualities such as readability, ease-of-use, and discoverability. Some C++ types are enablers in this regard: std::optional, std::variant, std::string_view/gsl::string_span, and, of course, […]
Goodbye, Q_FOREACH A porting guide to C++11 ranged for-loops
Q_FOREACH (or the alternative form, foreach) will be deprecated soon, probably in Qt 5.9. Starting with Qt 5.7, you can use the QT_NO_FOREACH define to make sure that your code does not depend on Q_FOREACH. You may have wondered what all the fuss is about. Why is there a continuous stream of commits going to into Qt […]