Finalizers for modules?

[jakebolewski]

I have had a couple of instances where this feature would be nice to have in terms of dealing with global state when interfacing with some external c-library. Thinking through some of the implications of #8745, it seems like it would be necessary to support pre-compiling packages in many instances (at least for some I have written).

[JeffBezanson]

When would this be called? At exit?

[jakebolewski]

At exit would be for the use cases I was thinking about. I don't know how module reloading would play into this.

[JeffBezanson]

Calling atexit in __init__ would probably work for that.

[jakebolewski]

calling atexit does not guarantee finalization order, so you can still have live objects with handles pointing to resources allocated within the library you are trying to close.

[vtjnash]

all atexit handlers are called before all finalizers which remain active at program exit. what is your desired order?

[jakebolewski]

It is a common pattern where objects retaining handles to allocated resources often free their resources when the object is gc'd. I guess the behavior I'm looking for is for the "module finalizer" to run after all other active finalizers have been run. This usually would be some ccall to the c library's teardown handler.