New submission from Serhiy Storchaka <storchaka+cpyt...@gmail.com>:
There is a flaw in the example in the documentation for contextlib.nullcontext.
def process_file(file_or_path):
if isinstance(file_or_path, str):
# If string, open file
cm = open(file_or_path)
else:
# Caller is responsible for closing file
cm = nullcontext(file_or_path)
with cm as file:
# Perform processing on the file
The execution can be interrupted by Ctrl-C between opening a file and entering
a 'with' block. There is the same problem with the simple "with open(path) as
file:", but it can be easily solved (see issue34066). It is harder to do for
this example, because there are more opcodes between calling open() and
entering 'with'. I afraid that this problem can't be solved in general case.
Maybe contextlib.nullcontext has a flaw similar to the flaw in
contextlib.nested().
----------
messages: 321226
nosy: ncoghlan, serhiy.storchaka
priority: normal
severity: normal
status: open
title: Problem with contextlib.nullcontext
type: resource usage
versions: Python 3.7, Python 3.8
_______________________________________
Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue34067>
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