On Wed, 03 Jun 2015 22:07:47 +1000, Steven D'Aprano wrote: > On Wed, 3 Jun 2015 07:38 pm, alister wrote: > >> On Wed, 03 Jun 2015 10:41:44 +0300, Marko Rauhamaa wrote: > [...] >>> Here's the deal: the child process is saddled with file descriptors it >>> never wanted in the first place. It can't decline them. Now you're >>> saying it can't even dispose of them. >>> >> No You cab dispose of them you just need to warn the user that the >> action did not complete correctly & there may be errors with the data. > > *What* action? Pay closer attention to what Marko wrote: > > "the child process ..." > > How does the child process know what action didn't complete? What error > message are you going to display to the user? > > "Error when closing file descriptor 123456" > > What action do you think the user can take on seeing this error message? > > >> Example What does your test editor do if you try to save a file back to >> a USB stick that has been removed? does it simply let you think the >> file has been successfully saved? i hope not. > > > Correct me if I'm wrong, but don't you get an error when you try to > *open* a file on a missing USB stick? > > There are at least three opportunities to get an error when writing a > file: > > * opening the file; > * writing to the file; > * closing the file. > > It's not clear what conditions will lead to the first two succeeding but > the third failing, or what to do if you get such an error. If you don't > know what caused close() to fail,
open file for appending data write some data remove mem stick now try to close file > then you can't do anything about it, Correct you cant do anything about it. > and if you can't do anything about it, what's the point in reporting the > error to the user who will just get frustrated and nervous and not be > able to do anything about it either? Because they need to know they may have just lost important data whilst they still have a chance to do it again. finding out 6 months later that they had screwed up saving data on a multi-million pound account will not be good & quite rightly considered to be due to a bug in your software. > > I'm sure that there are circumstances where an error when closing a file > is a clear and obvious fault that should be reported. But in the > scenario that Marko is describing, I'm not so sure that is the case. from the scenario Marco is reporting I get the impression that he is having to interact with a system that is fundamentally flawed from the ground up. -- Standards are crucial. And the best thing about standards is: there are so ____many to choose from! -- https://mail.python.org/mailman/listinfo/python-list
