Hi, it seems Python’s GC runs FIFO, which is causing a slight problem with my AutoCAD wrappers Database is a collection of dbobjects that may be opened for read or write Database std::shared_ptr that is deleted in the dtor Dbobject is a std::shared_ptr that calls ptr->close() in the dtor Python GC…

Thanks for the reply. in most every other programing language, variables are dropped in the reverse order of their initialization. I can’t be the first wrapper writer to run into this issue. import traceback from pyrx import Db, Ed, Ge, Ap, Rx, Gs class A: def __init__(self, name): se…

This is kind of the pattern I plan on putting in my sample, but it looks kludgy import traceback from pyrx import Db, Ed, Ge, Ap, Rx, Gs class DbChild: def __init__(self, name): self.name = name print(f"Object {self.name} created") def __del__(self): print(f"Object…

What if makeChild actually registered the new object as the caller instance’s child? What’s important here is that the parent holds a reference to its children: def __init__(self, name): self.name = name self.children = [] print(f"Object {self.name} created") def makeChild(self, name):…

Thanks for the reply! I’m still learning Python, my sample was just to illustrate how the destruction order differs. I think adding the child as a reference to the parent won’t work in my case, It’s the opposite direction, maybe adding a reference of the parent to the child could work.

[image] Dan: Are there elegant patterns in Python to simulate the behavior one might get from other languages? Not really, because pretty much everything you’re discussing here is an implementation detail. There’s nothing you can really do to guarantee the behavior you want. Note the follow…

Hi, thanks for the reply This is really an edge case in the project Python’s GC is actually very deterministic; I spent the first six months of the project studying the behavior so I would not end up in the same mess as .NET wrappers. There’s pretty good unit test coverage on the lifetime of AutoC…

Generally (non-memory) resources are managed using with blocks which are probably the closest analogy to c# using blocks. [image] CEXT-Dan: Python’s GC is actually very deterministic I think that’s for a specific Python implementation for a specific Python version. E.g. if you were to run it…

Hi, Yes, I’m running in an embedded context, inside AutoCAD’s process. I’m linked to 3.12.X, and wxWidgets(wxPython) for MFC wrappers I used boost::python, all hand rolled with love, except I wanted to gouge my eyes out doing the ActiveX wrappers :grin: Anyway, it’s very fast. Just the best scrip…

In my opinion, you should definitely codify your dependencies. Suppose that in your example, where you create A, B, and C, that you create a pointer to C. Now you say that the GC should not delete A and B? How is it supposed to know?

Hi, Sorry for the confusion, I was trying to illustrate the behavior in the simplest terms If you read my original post: Database std::shared_ptr that is deleted in the dtor only the Database is deleted when ref count reaches zero. Dbobject is a std::shared_ptr that calls ptr->close() in the dt…

Delay GC on object

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Alex-Wasowicz (Aleksander Wąsowicz) October 30, 2025, 7:32am 14

So DbObjects depends on Database.

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