Re: [Python-ideas] Generator-based context managers can't skip __exit__

Ram Rachum wrote: 1. I'm making a program that lets people lease machines. They can issue a command to lease 7 machines. ... If everything goes fine, I do pop_all on the exit stack so it doesn't get exited and the machines stay leased, Seems to me that would be done more easily and clearly

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 11/18/2016 12:42 PM, Ram Rachum wrote: Sure, here are a couple of use cases: 1. I'm making a program that lets people lease machines. They can issue a command to lease 7 machines. When they do, my program leases them one by one and adds them all to an exit stack, so in case there aren't 7

Re: [Python-ideas] Generator-based context managers can't skip __exit__

Sure, here are a couple of use cases: 1. I'm making a program that lets people lease machines. They can issue a command to lease 7 machines. When they do, my program leases them one by one and adds them all to an exit stack, so in case there aren't 7 machines available, all the machines we leased

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 06.11.2016 09:07, Steven D'Aprano wrote: I'm having a lot of difficulty in understanding your use-case here, and so maybe I've completely misunderstood something. Although, this thread is dead for a week or so, I am still curious to hear the real-world use-case. I am equally puzzled by

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 11/06/2016 08:11 PM, Nick Coghlan wrote: On 7 November 2016 at 12:25, Ethan Furman 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.

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 7 November 2016 at 12:25, Ethan Furman 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

Re: [Python-ideas] Generator-based context managers can't skip __exit__

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. -- ~Ethan~ ___ Python-ideas mailing list Python-ideas@python.org

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 11/06/2016 12:18 AM, Ram Rachum wrote: Well, you think it's weird that I want a `finally` clause to not be called in some circumstances. Yes I (we) do. Do you think it's equally weird to want an `__exit__` method that is not called in some circumstances? Yes I (we) do. -- ~Ethan~

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 11/6/2016 2:18 AM, Ram Rachum wrote: Well, you think it's weird that I want a `finally` clause to not be called in some circumstances. Do you think it's equally weird to want an `__exit__` method that is not called in some circumstances? Without a deeper understanding of why you want to do

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 6 November 2016 at 17:44, Ram Rachum wrote: > I understand your point of view. I see that Python does allow you to not > call `__exit__` if you don't want to, so I wish it'll have the same approach > to not calling `generator.close()` if you don't want to. (This is what it's >

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On Sun, Nov 06, 2016 at 06:46:40AM +0200, Ram Rachum wrote: > Hi everyone, > > Here is a simplification of a problem that's been happening in my code: > > import contextlib > > @contextlib.contextmanager > def f(): > print('1') > try: > yield > finally: > print('2')

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On Sun, Nov 6, 2016 at 9:38 AM, Nick Coghlan wrote: > On 6 November 2016 at 17:18, Ram Rachum wrote: > > On Sun, Nov 6, 2016 at 8:53 AM, Nick Coghlan wrote: > >> There's still something seriously odd going in relation to your > >>

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 6 November 2016 at 17:18, Ram Rachum wrote: > On Sun, Nov 6, 2016 at 8:53 AM, Nick Coghlan wrote: >> There's still something seriously odd going in relation to your >> overall resource management architecture if "cleanup, maybe, unless I >> decide to tell

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 2016-11-06 00:18, Ram Rachum wrote: Well, you think it's weird that I want a `finally` clause to not be called in some circumstances. Do you think it's equally weird to want an `__exit__` method that is not called in some circumstances? It's weird to not want the __exit__ to be called if

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On Sun, Nov 6, 2016 at 8:53 AM, Nick Coghlan wrote: > On 6 November 2016 at 16:07, Ram Rachum wrote: > > Heh, I just played with this, and found a workaround. If I do something > like > > this after creating the generator: > > > > sys.g = g > > > > Then it

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 6 November 2016 at 16:07, Ram Rachum wrote: > Heh, I just played with this, and found a workaround. If I do something like > this after creating the generator: > > sys.g = g > > Then it wouldn't get closed when Python finishes, and the cleanup won't > happen, which is what I

Re: [Python-ideas] Generator-based context managers can't skip __exit__

Heh, I just played with this, and found a workaround. If I do something like this after creating the generator: sys.g = g Then it wouldn't get closed when Python finishes, and the cleanup won't happen, which is what I want. This is still a bit ugly but now it's something I can do automatically

Re: [Python-ideas] Generator-based context managers can't skip __exit__

Sorry, I was wrong at quoting the workaround I do, it's actually this: try: yield except GeneratorExit: raise except: cleanup() raise else: cleanup() This works, but

Re: [Python-ideas] Generator-based context managers can't skip __exit__

On 6 November 2016 at 14:46, Ram Rachum wrote: > I worked around this problem by adding `except GeneratorExit: raise` in my > context manager, but that's an ugly solution. Adding `except GeneratorExit: raise` to a try statement with a finally clause won't prevent the finally