How does the "toString" method of qt data structures work?
I found myself trying to save the textual representation of a QVariantMap (QMap<QString, QVariantMap>> actually) like as if I were to write
qDebug() << myMap
which yields the correct text data put to the console, but instead have the result in a file. I tried with QDataStream class but it can only handle binary form, I managed to do it finally like this:
outDebug << myMap;
But it really bothers me that I have no idea what is going on behind the scenes. I assume either
QDebug & QDebug::operator<<(const QByteArray & b)or
QDebug & QDebug::operator<<(const QString & s)functions are called after an implicit conversion, but how does that implicit conversion work?
Also I have a custom (non-QObject)! class that is among the stored QVariants and it's textual repesentation is an empty string. Is there a way to customize that?
friend QDataStream & operator << (QDataStream & out, const YourClass& t)
out << t._nom;
That'll work, ty, but how come a QDebug instance can decompress the binary to textual? And how does one do it without QDebug instance?
And actually I can't make your code snippet work. I implemented the friend operator method as described by you and doc but it's not called like it should be.
Have a look at the QDebug documentation, there's an example on how to write a debug stream operator for your custom type.
Aha, I see, somehow I skipped trough that paragraph of the doc, thanks!