How to properly subclass QIODevice -- understanding the docs

[ChrisW67]

QIODevice keeps a track of the number of bytes read (i.e. the pos()) and allows you to skip about with seek(). If your subclass implements a seek() override that does something special, or some other function that affects the current position, it should call QIODevice::seek() so the base class is updated properly. That is:

bool	MyIODevice::seek ( qint64 pos ) {
  QIODevice::seek(pos);
  // Do your sub-class magic with pos here
  // e.g. if you need to issue commands to hardware to rewind to the corresponding position
}

bool	MyIODevice::seek ( qint64 pos ) {
  QIODevice::seek(pos);
  // Do your sub-class magic with pos here
  // e.g. if you need to issue commands to hardware to rewind to the corresponding position
}

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If you do not override the base class seek() then you don't need to do anything special.