Where is the documentation for the internals of Qt and the design patterns used for building it

Question

Please point the docs for understanding the internals of Qt such as the design of the QObject class, The patterns choosen for the Qt classes. The reason for using QVariant class, e.t.c. Although Qt comes with very good documentation and examples, they mostly explain how to use them not why it is being done that way.

Answer 1

Here is a blog entry that at least explains the use of private classes and d-pointers in Qt. Qt-Howto

Answer 2

I can't begin to answer this authoritatively, but some good resources are the description of the Qt Object Model and the QObject class reference, and the first half of this document for demystifying some of the Qt internals like signals and slots. Some of the design justifications are discussed here - why they use syntactic sugar, code generators etc.