On 15 April 2018 at 11:22, Elazar <elaz...@gmail.com> wrote: > בתאריך יום א׳, 15 באפר׳ 2018, 13:13, מאת Serhiy Storchaka > <storch...@gmail.com>: >> Actually the reliable code should write into a separate file and replace >> the original file by the new file only if writing is successful. Or >> backup the old file and restore it if writing is failed. Or do both. And >> handle hard and soft links if necessary. And use file locks if needed to >> prevent race condition when read/write by different processes. Depending >> on the specific of the application you may need different code. Your >> three lines are enough for a one-time script if the risk of a powerful >> blackout or disk space exhaustion is insignificant or if the data is not >> critical. > > This pitfall sounds like a good reason to have such a function in the > standard library.
It certainly sounds like a good reason for someone to write a "safe file rewrite" library function. But I don't think that it's such a common need that it needs to be a stdlib function. It may well even be the case that there's such a function already available on PyPI - has anyone actually checked? And if there isn't, then writing module and publishing it there would seem like a *very* good starting point - as well as allowing the developer to thrash out the best API, it would also provide for lots of testing in unusual scenarios that the developer may not have thought about (Windows file locking is very different from Unix, what is an atomic operation differs between platforms, error handling and retries may be something to consider, etc). The result would be a useful package, and the download and activity stats for it would be a great indication of whether it's a frequent enough need to justify including in core Python. IMO, it probably isn't. I suspect that most uses would be fine with the quoted 3-liner, but very few people would need the sort of robustness that Serhiy is describing (and that level of robustness *would* be needed for a stdlib implementation). So PyPI is likely a better home for the "bulletproof" version, and 3 lines of code is a perfectly acceptable and Pythonic solution for people with simpler needs. Paul _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
