call up, notify down

[Uwe Mayer]

Hi,

someone told me this on how layered-architectures work. It took me some time
to read-up to it, but now I think its rather the other way around:

The lower layers provide functionality to upper layers. Therefore it should
be: call down, notify up.
Qt does it the same way, as I understood it: You call the public methods of
underlying objects and can install SIGNALs to be notified (notify up).

This flips if I misunderstood the meaning of up and down, but to me "down"
means the more fundamental components. Going up from a root-node.

Ciao
Uwe