[Qt-interest] why signals are not objects?

[Volker Hilsheimer]

"Luca Ferrari" <fluca1978 at infinito.it> wrote in message 
news:200905041111.30614.fluca1978 at infinito.it...
> Ok, maybe a trivial question, but I didn't find anything about in the
> archives: why signals are not implemented as c++ objects? Should not be
> simpler the implementation of the signal/slot mechanism? I agree that 
> the moc
> provides more expressiveness but objects have a simpler implementation.
> So, what is the reason for choosing the moc instead of a set of classes?
>
> Luca


With the current solution you can introspect the signals provided by a 
class without having an instance of that class (you only need the static 
QMetaObject), and instances of that class carry no additional cost for the 
signals declared (connections of course cost dynamic memory anyway).

Implementing signals as member objects adds cost to class instances, which 
is not acceptable. Of course you can make the signal objects static class 
members, but then you don't have much left in terms of simplicity or 
convenience, given that moc is required for other things anyway.

Volker