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Using Qt 6 under LGPLv3

The Qt Company changed Qt licensing in February 2022. All the separate commercial packages – including Qt for MCU, Qt Safe Renderer, Qt Automotive Suite and Qt Automation – were folded into two Qt for Device Creation licenses: Professional and Enterprise. The Qt Marketplace license for modules like CoAP, MQTT, Charts and for the design tool bridges was discontinued. My post helps you answer the crucial question: Shall you use Qt Commercial or Qt LGPL-3.0?

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Applying TDD to Classes Accessing Files

We start with unit tests reading a file line by line with QFile. Unit tests accessing the file system are not considered unit tests, as they may be slow and may depend on each other in surprising ways (see A Set of Unit Testing Rules by Michael Feathers). In a first step, we encapsulate QFile in a class TextFile and provide a fake implementation representing the file as a list of strings kept in main memory. In a second step, we introduce an interface, from which the product and fake implementations derive. We can now apply TDD to classes accessing files.

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Ports-and-adapters architecture for harvester terminal with GUI, Cloud, Machine and Customer adapter.

My Talk “A Successful Architecture for Qt Embedded Systems” at Qt Day Italy 2021

Creating an architecture means answering many questions about the ecosystem, in which the Qt embedded system operates. While the questions are very similar for all Qt embedded systems, the answers and their priorities differ. So, you should be able to transfer the questions and answers from my running example, a harvester terminal, to your system.

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Window manager showing split view of home (left) and of turbine cam (right).

Architecture of Qt Embedded Systems: Single vs. Multiple GUI Applications

Our quest for a successful architecture of a harvester terminal continues. In this episode, we discuss when a system with a single application is good enough and when a system with multiple applications and a window manager is the better choice. Sometimes, a single-application system with a window manager is just the right choice.

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