New submission from Ezio Melotti:
Add an itercm() function that receives an iterable that supports the context
manager protocol (e.g. files) and calls enter/exit without having to use the
with statement explicitly.
The implementation is pretty straightforward (unless I'm missing something):
def itercm(cm):
with cm:
yield from cm
Example usages:
def cat(fnames):
lines = chain.from_iterable(itercm(open(f)) for f in fnames)
for line in lines:
print(line, end='')
This will close the files as soon as the last line is read.
The __exit__ won't be called until the generator is exhausted, so the user
should make sure that it is (if he wants __exit__ to be closed). __exit__ is
still called in case of exception.
Attached a clearer example of how it works.
Do you think this would be a good addition to contextlib (or perhaps itertools)?
P.S. I'm also contemplating the idea of having e.g. it = itercm(fname,
func=open) to call func lazily once the first next(it) happens, but I haven't
thought in detail about the implications of this. I also haven't considered
how this interacts with coroutines.
----------
components: Library (Lib)
files: itercm-example.txt
messages: 249991
nosy: ezio.melotti, ncoghlan, rhettinger
priority: normal
severity: normal
stage: needs patch
status: open
title: Add contextlib.itercm()
type: enhancement
versions: Python 3.6
Added file: http://bugs.python.org/file40380/itercm-example.txt
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