New submission from Owen Pembery <opemb...@gmail.com>:
This may be a bug, or may be a hole in my understanding of how importlib.reload works. In short, when running importlib.reload in a script, it seems that a module is not reloaded before it is used, whereas running the same script a line at a time in interactive mode seems to reload the script. Relevant scripts are in the github repository: https://github.com/orpembery/python-reload-bug. I find the bug using python 3.5.2 on Ubuntu 16.04. The expected output from running python3 master.py is: 1 2 However, I instead find that the output is: 1 1 If I paste the commands in master.py into the interpreter one at a time, I get the expected behaviour: Python 3.5.2 (default, Nov 12 2018, 13:43:14) [GCC 5.4.0 20160609] on linux Type "help", "copyright", "credits" or "license" for more information. >>> from shutil import copy >>> >>> from importlib import reload >>> # Move a file ... copy('fn_1.py','fn.py') 'fn.py' >>> # Import it ... import fn >>> # Run it ... fn.fn() 1 >>> # Move a different file to the same location. ... copy('fn_2.py','fn.py') 'fn.py' >>> # Reload it ... reload(fn) <module 'fn' from '/home/owen/code/python-reload-bug/fn.py'> >>> # Run it ... fn.fn() 2 However, if the commands in master.py are pasted in all at one (i.e., with a single CTRL-V keystroke), I obtain the unexpected behaviour: Python 3.5.2 (default, Nov 12 2018, 13:43:14) [GCC 5.4.0 20160609] on linux Type "help", "copyright", "credits" or "license" for more information. >>> from shutil import copy >>> from importlib import reload >>> >>> # Move a file ... copy('fn_1.py','fn.py') 'fn.py' >>> >>> # Import it ... import fn >>> >>> # Run it ... fn.fn() 1 >>> >>> # Move a different file to the same location. ... copy('fn_2.py','fn.py') 'fn.py' >>> >>> # Reload it ... reload(fn) <module 'fn' from '/home/owen/code/python-reload-bug/fn.py'> >>> >>> # Run it ... fn.fn() 1 Possible causes: I'm very far from an expert, but it seems to be something to do with caching; running python3 -B master.py gives the expected behaviour. ---------- components: Library (Lib) messages: 330631 nosy: brett.cannon, orpembery priority: normal severity: normal status: open title: Importlib.reload has different behaviour in script and interactive mode versions: Python 3.5 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue35343> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
