As to obviating the need for emitting a signal by installing an event filter — well, that's one of those better ideas I was hoping for, along with the C++11 ampersand method mentioned by the other André (thanks to both of you).
Maintaining a connection — I didn't want to, hence the disconnect(Button9,0,0,0) — I wanted to establish a temporary one at the activated window's discretion. On Mon, Jan 30, 2017 at 10:41 AM, André Somers <an...@familiesomers.nl> wrote: > Hi, > > > Op 28/01/2017 om 01:33 schreef Forrest Leeson: > >> Assume an application that creates a focusable dialog with 9 buttons. >> Clicking buttons 1-8 causes the creation of new windows — type 1 >> through type 8, each type supporting a slot, S, that can be connected >> to the signal of button 9. >> >> Clicking button 9 should trigger slot S only of the window that was >> most recently active. Which is to say the connection can't usefully be >> set up when the window is created. >> >> A solution would seem to be to add a look-at-me signal to all the >> window types, which they would emit to the dialog upon receiving >> focus; the receiver would then [ disconnect(Button9,0,0,0) ] and then >> connect Button 9 to the signalling window's slot S by way of >> QObject::sender() with a side order of qobject_cast...at which point I >> am realize I am stupid and ignorant and have misplaced all my B >> vitamins and choline supplements and my coffee is cold and foul. >> The documentation warns against using Sender this way, but chides >> rather than forbids. Look-at-me signals not arriving in order would be >> a dealbreaker, but unless I'm misreading, establishing the connection >> with Qt::DirectConnection will fix that. And I guess checking for 0 >> against the result of the cast will avoid crashing. >> >> So: is this approach even minimally sane, and even if so is there a >> (better) way to do it? > > Why do you maintain a connection to each of the windows at all? It seem to > me that it would be much easier keeping track of which of your windows 1..8 > is active (monitor for the occurance of QEvent::WindowActivate in your > application via an event filter), and then on triggering button 9 simply > call the indicated method S on that window. > > André > > _______________________________________________ > Interest mailing list > Interest@qt-project.org > http://lists.qt-project.org/mailman/listinfo/interest _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
