I have a PyQt QWidget (object A; it is just a pasive container) that contains several child widgets (i.e. there are Qt'ish parent-child references). A's child widgets are referenced from another object (object B; not necessarily a Qt object) that feeds A's children with data and actually controls the creation and structure of the A's children. Apart from A's children, object B has no other outer references. Object A has a reference to object B. So, it is a pure textbook example of circular references.
I want, at some time point, delete the whole interconnected structure of objects A and B. I simply call A.deleteLater() which is recommended for Qt objects. It seems to me that it works fine and deletes A and B because they have no outer references, just the mutual ones... but the thing is that I am not very sure about if it really works, if it can be relied upon it will work everywhere and if there are any dangers if someone will subclass B for example.
For debugging purposes I wanted to observe proper destruction of A and B using __del__ destructor that would just print something like A was destroyed. But then I learned in the docs that when __del__ is present, the garbage collector will not collect such objects with circular references. Does this mean that observing the destruction will affect or cancel the destruction? If I am right this seems to be something like quantum mechanics - the existence of observer that affects the result of an experiment.
So basically there are two questions:
is this use of
deleteLater()correct and reliable? andDoes message printing in
__del__destructor affect the garbage collector? Or what other ways I can use to observe and confirm destruction during debugging?