Python: flush a buffer before program termination via a finalizer

Question

I keep a cache of transactions to flush (to persistent storage) on the event of a watermark or object finalization. Since __del__ is no longer guaranteed to be called on every object, is the appropriate approach to hook a similar function (or __del__ itself) into atexit.register (during initialization)?

If I'm not mistaken, this will cause the object to which the method is bound to hang around until program termination. This isn't likely to be a problem, but maybe there's a more elegant solution?

Note: I know using __del__ is non-ideal because it can cause uncatchable exceptions, but I can't think of another way to do this short of cascading finalize() calls all the way through my program. TIA!

Answer 1

If you have to handle ressources the prefered way is to have an explicit call to a close() or finalize() method. Have a look at the with statement to abstract that. In your case the weakref module might be an option. The cached object can be garbage collected by the system and have their __del__() method called or you finalize them if they are still alive.