Giuseppe D’Angelo

You know the drill: in C++ you need to #include header files that declare the types and functions from the libraries that you use. Qt is no exception in this regard. Qt follows a very nice convention for its own datatypes: if you need to use a type called QType, then use #include <QType>. This […]

A few days ago, a customer using our KD Soap library reported an interesting problem with it. The library worked perfectly to access the SOAP server, but there was some noticeable latency when doing a series of requests in short succession from the client. This latency should not have been there, as both the server […]

Today's blog post is about something that should be simple and apparently it causes trouble: how to declare a qHash overload for a custom datatype. This is necessary when we want to use custom datatypes as keys in a QHash. From the documentation: A QHash's key type has additional requirements other than being an assignable […]

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 […]

Did you miss the past Qt World Summit? Were you there, but you couldn't attend that talk or two that you really wanted to see because the conference was so, so packed with awesome content? Fear no more! We are glad to announce that the talks at the past Qt World Summit 2019 in Berlin […]

A few days ago Marc Mutz, colleague of mine at KDAB and also author in this blog, spotted this function from Qt's source code (documentation): Apart from the mistake of considering empty strings not uppercase, which can be easily fixed, the loop in the body looks innocent enough. How would we figure out if a […]

While the concept of multithreading may be straightforward, code with threads is responsible for some wicked bugs, which can be nearly impossible to reproduce or track down. This makes writing bullet-proof code using threads a tall order. Let's look a little deeper into why that is. First, you need better than average knowledge about the […]

Continuing our blog series about KDToolBox, this time we will discuss UiWatchDog, a keepalive monitor for the GUI thread. Alive? A fundamental rule when writing applications in event-driven UI frameworks such as Qt is: do not ever block the GUI thread! The GUI thread is also usually called the main thread of the application -- […]

With this blog post we are going to kickstart our brand new blog series about KDToolBox. The first class we're exploring is KDTableToListProxyModel, a table-to-list proxy model. The main use case for KDTableToListProxyModel is exposing tabular models to Qt Quick. Qt Quick has a certain number of "view" elements that only support list models: for […]

At KDAB we invest a significant amount of efforts in research and development. We are always looking for new tooling, libraries and utilities that can make our job easier and improve the C++ and Qt ecosystems. Ultimately, the gained knowledge and skills make our customers happier. As part of this process we develop lots of […]

In the last episode of this series we discussed QAbstractItemModel::checkIndex(). QAbstractItemModel::checkIndex() is a function added in Qt 5.11 that allows developers of model classes to perform some validity checks on the QModelIndex objects passed to the model; specifically, on the indices passed to the APIs that model classes need to implement (rowCount(), columnCount(), data, setData(), […]

The Qt model/view APIs are used throughout Qt -- in Qt Widgets, in Qt Quick, as well as in other non-GUI code. As I tell my students when I deliver Qt trainings: mastering the usage of model/view classes and functions is mandatory knowledge, any non-trivial Qt application is going to be data-driven, with the data […]

QtDay is the yearly Italian conference about Qt and Qt-related technologies. Its 2018 edition (the seventh so far!) will be once more in the beautiful city of Florence, on May 23 and 24. And, once more, KDAB will be there. I am also glad to announce that my talk has also been accepted: I am […]

The program for CppCon 2017 is now published! CppCon is the annual conference for the C++ community: five days packed with over 100 talks, as well as inspiring keynotes, panel discussions, hallway chats, fun evening events and much more. CppCon is a project of the Standard C++ Foundation, a not-for-profit organization whose purpose is to […]

Property bindings are one of the most interesting features of the QML language. In QML, when we set a value on a property, the right hand side expression isn't evaluated just once to produce a value, like in a ordinary imperative language. In particular, if the expression involves other properties, then the property we're setting […]

Qt 5.9 has just been released! This release marks two important milestones for the Qt Project. The first is that now the Qt 5 series has had more releases than any other Qt version ever (the last release of the Qt 4 series was Qt 4.8). The second milestone is that Qt 5.9 will be […]

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 […]

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 […]

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 […]