Re: [PyQt] Shouldn't an item view keep a reference to its associatedmodel?
Hans-Peter Jansen <[EMAIL PROTECTED]> wrote: > and next time, you're facing empty widgets unexpectedly, it will ring a huge > bell somewhere between your ears.. ;-) Oh, yes. I guess this is a typical beginner's mistake. ;-) BTW: thank you very much for PyQt (and thanks to Qt developers if some of them are here). I find it very pleasant to use and am impressed by the quality (as far as I can judge) of the API and the Qt documentation. Florent ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
Re: [PyQt] Shouldn't an item view keep a reference to its associatedmodel?
Am Freitag, 20. Juli 2007 13:00 schrieb Florent Rougon: > Giovanni Bajo <[EMAIL PROTECTED]> wrote: > > It is not what Qt does. PyQt doesn't play tricks with object lifetimes: > > it exposes Qt's underlying object model. > > [...] > > OK, thanks to you and Phil for the answers. It makes sense now. and next time, you're facing empty widgets unexpectedly, it will ring a huge bell somewhere between your ears.. ;-) Pete ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
Re: [PyQt] Shouldn't an item view keep a reference to its associatedmodel?
Giovanni Bajo <[EMAIL PROTECTED]> wrote: > It is not what Qt does. PyQt doesn't play tricks with object lifetimes: it > exposes Qt's underlying object model. [...] OK, thanks to you and Phil for the answers. It makes sense now. Regards, -- Florent ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
Re: [PyQt] Shouldn't an item view keep a reference to its associatedmodel?
On Friday 20 July 2007 11:17 am, Giovanni Bajo wrote: > On Fri, 20 Jul 2007 11:56:38 +0200, Florent Rougon <[EMAIL PROTECTED]> > > wrote: > > I thought it should be possible to have the views keep a reference to > > their model without "owning" it, as you say. For instance: > > > > view1.setModel(model) > > > > internally would do 'view1.model = model' > > > > and similarly, > > > > view2.setModel(model) > > > > internally would do 'view2.model = model', so that 'model' cannot get > > garbage-collected as long as either 'view1' or 'view2' is alive. > > > > What's wrong with this approach? > > It is not what Qt does. PyQt doesn't play tricks with object lifetimes: it > exposes Qt's underlying object model. > > In Qt, when you call setModel() the model owenrship isn't transferred to > the view. The model still has a separate lifetime, and you need to take > care of it, and explicitly delete the model when you don't need anymore; > or, as Phil suggested, make the model child of an object that takes its > ownership (such as: the view), so that it gets destroyed when the parent is > destroyed as well. So, having the setModel() call take an additional > reference to the model would break the orthogonality between Qt and PyQt. > > Whatever problem you're facing, you would be having it in C++ as well. Try > and see how C++ programmers solve it, and do the same. No, in C++ you would have a memory leak but your code would still work. Phil ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
Re: [PyQt] Shouldn't an item view keep a reference to its associatedmodel?
On Fri, 20 Jul 2007 11:56:38 +0200, Florent Rougon <[EMAIL PROTECTED]> wrote: > I thought it should be possible to have the views keep a reference to > their model without "owning" it, as you say. For instance: > > view1.setModel(model) > > internally would do 'view1.model = model' > > and similarly, > > view2.setModel(model) > > internally would do 'view2.model = model', so that 'model' cannot get > garbage-collected as long as either 'view1' or 'view2' is alive. > > What's wrong with this approach? It is not what Qt does. PyQt doesn't play tricks with object lifetimes: it exposes Qt's underlying object model. In Qt, when you call setModel() the model owenrship isn't transferred to the view. The model still has a separate lifetime, and you need to take care of it, and explicitly delete the model when you don't need anymore; or, as Phil suggested, make the model child of an object that takes its ownership (such as: the view), so that it gets destroyed when the parent is destroyed as well. So, having the setModel() call take an additional reference to the model would break the orthogonality between Qt and PyQt. Whatever problem you're facing, you would be having it in C++ as well. Try and see how C++ programmers solve it, and do the same. -- Giovanni Bajo ___ PyQt mailing listPyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
