On 7 November 2016 at 12:25, Ethan Furman <et...@stoneleaf.us> wrote: > On 11/06/2016 12:44 AM, Ram Rachum wrote: > >> I see that Python does allow you to not call `__exit__` if you don't want >> to [...] > > Um, how? I was unaware of this (mis-)feature.
It involves wrapping the context manager in another context manager that deliberately doesn't delegate the call to __exit__ in some cases (cf contextlib.ExitStack.pop_all()). By contrast, if __del__ is defined (as it is on generators), if you don't keep the context manager itself alive, you can only prevent the cleanup happening if you can define a subclass to use instead, and that's not always possible (deliberately so, in the case of generator cleanup). So the odd part of Ram's request isn't wanting to have conditional resource cleanup - the recipes in the contextlib docs gives some examples of where conditional local resource management is useful and how to achieve it using ExitStack. The odd part is wanting to make the resource cleanup implicitly unreliable, rather than having it be reliable by default and folks having to explicitly opt in to disabling it, since the easiest way to obtain non-deterministic resource management is to just avoid using the context management features in the first place. Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
