On Tuesday 08 January 2008, Aaron Digulla wrote: > Quoting Phil Thompson <[EMAIL PROTECTED]>: > > I'm happy to consider ways to make this more obvious (even if it's just a > > better FAQ), but I'm not happy about departing from the Qt API and > > introducing inconsistencies in fundamental behaviour. > > Then let me put it this way: If I wanted to care about who calls the > dtor, I'd be using C++ and not Python. ;-) > > As a Python developer, I expect PyQt to behave like python code: As > long as anyone (my code, PyQr or Qt) still has references to some > object, the dtor must not be called, no matter what and PyQt as a > *python* wrapper for Qt should follow the Python rules, not the Qt > rules, especially not in a case where there is no conflict.
Then your expectations are misplaced. Are you seriously suggesting that PyQt somehow stops Qt calling a dtor? > As I see it, managing the reference counter in setModel() is an easy > fix, it doesn't break the Qt API and it makes PyQt behave like any > Python expects. So what is the specific point not to do it? > > As for "ownership": Qt had to introduce this concept to avoid memory > leaks. This is not necessary in Python (because Python handles this > behind the scenes), so I suggest to ignore all "ownership"-style calls > and/or wrap them in the Pyhton equivalent (to makes sure that objects > aren't GC'd as long as someone still needs them). I'd guess that would > fix most of the issues with little effort on your side plus reduce the > amount of discussion and "I don't understand"-like mails considerably. > > The ultimate goal should be to have > > edit.setDocument(QTextDocument(edit)) > > and > > edit.setDocument(QTextDocument()) > > behave the same way: Make sure that QTextDocument() lives as long as > edit needs it. Pseudocode: > > setModel(model): > if model(): > if isPython(model()): model().refount-- > elif model().owner == NULL: ShouldNotHappenException > if model: > if isPython(model): model.refount++ > else: > # Someone tried the Qt style -> avoid > model.owner = NULL # Owner is Python[1] > model = PyWrapper(model) > model.refount++ > super.setModel(model) > > In this code, you could also print a warning if someone used > QTextDocument(edit) or install a python GC object as the owner of the > model which manages the relationships (face it: A model is not going > to be used by more than 10..100 parents, so we could simply store > everything in a map or list or something). > > Alternatively, you could add a thin wrapper for PyQt which works the > Python way and print a warning if setModel() is called with a > QTextDocument() which has no owner. Then users who don't want to care > about dtor calling could use PyQTextDocument(), etc. instead. > > PS: Without your mail, I still wouldn't have a clue as to what is > going on. There are some traces of information about this in the FAQ > and elsewhere but they are far from easy to understand even after > knowing your explanation. So if you refuse to fix the non-python > behavior of PyQt, then please at least fix the documentation: > http://www.riverbankcomputing.co.uk/pyqt/faq.php > http://www.riverbankcomputing.com/Docs/PyQt4/pyqt4ref.html#garbage-collecti >on and > http://www.riverbankcomputing.com/Docs/PyQt4/html/qtextedit.html#setDocumen >t > > These may seem clear to you but as a Python developer, I don't know > why I should care that "[t]he parent QObject of the provided document > remains the owner of the object." Only after reading all three > documents, it becomes clear that "owner" means "who GCs the > object/makes sure that it isn't GCd" (or calls the dtor). Documentation patches welcome. Phil _______________________________________________ PyQt mailing list PyQt@riverbankcomputing.com http://www.riverbankcomputing.com/mailman/listinfo/pyqt
