I started writing first articles about programming containing reusable source code more than six years ago, inspired by websites like CodeGuru and CodeProject which were an invaluable source of information when I was learning Visual C++ and MFC. They are still available here and remain the most popular section of my website. The idea of reusing code is even more important in open source development, but it took many years until I finally decided to start publishing articles related to Qt.
At the moment I'm extracting reusable components from the WebIssues Client code and writing documentation and demo applications for them. The first article called Simple template-based relational database is already available. It describes the data container invented for and used by the WebIssues Client, which is an interesting and innovative alternative to using a hierarchy of objects to store application data in memory.
Though WebIssues is licensed under the GPL, I decided to relicense all reusable components using the revised BSD-style license, which allows to use them in both open source and commercial applications. If you use the code for commercial purpose, please consider making a donation to the author. I will also happily answer all questions, requests and bug reports on the forums.
Another article I wrote some time ago describes the Generator core component of Fraqtive. I'm publishing it because it may be a good source of knowledge for someone who wants to learn metaprogramming on a practical example. The generator core is the most advanced piece of code that I've ever written in C++. It turned out to be an excellent exercise field, because the code is relatively small and simple, yet it allowed me to use a large number of various programming techniques, including metaprogramming with complex class templates.