I'm new to python.
I wonder if I write:
open('/tmp/xxx.txt', 'w+').write('aabb')
Will the file be still opened or closed?
In another word, what's the difference between the above and
with open('/tmp/xxx.txt', 'w+') as f:
f.write('aabb')
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Nan Hua
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1Not sure why this is downvoted, it's a clearly stated and on-topic question. – flornquake Sep 27 '16 at 18:45
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@flornquake might be because it lacks research. I'm certain the official documentation covers these cases. – vaultah Sep 27 '16 at 18:47
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@ŁukaszRogalski How can you conclude that this question is a duplicate of that one? – Vincent Savard Sep 27 '16 at 18:48
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1@vaultah: [It does.](https://www.python.org/dev/peps/pep-0343/) – Jan Sep 27 '16 at 18:49
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@ŁukaszRogalski, @Jan, `with` is a mere half of the question. – zneak Sep 27 '16 at 18:50
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@vaultah, how does the question you've linked to addresses the reference counting questions? – zneak Sep 27 '16 at 18:53
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@zneak please read the first two answers. – vaultah Sep 27 '16 at 18:54
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@vaultah, none of the answers say anything about the lifetime of a variable that isn't captured. – zneak Sep 27 '16 at 18:59
1 Answers
2
The file might stay open.
Keep in mind that it will be automatically closed upon garbage collection or software termination but it's a bad practice to count on it as exceptions, frames or even delayed GC might keep it open.
Also, you might lose data if the program terminated unexpectedly and you don't flush() it.
In many distributions of python, where the GC is different (PyParallel for example) it might cause a big problem.
Even in CPython, it might still stay open in case of frame reference for example. Try running this:
import sys
glob_list = []
def func(*args, **kwargs):
glob_list.append((args, kwargs))
return func
sys.settrace(func)
open('/tmp/xxx.txt', 'w+').write('aabb')
Bharel
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Specifcally, in cpython, it will likely be immediately closed. In other implementations of Python with differing GC semantics, it may stay open (and possibly unwritten) for quite some time. – Max Sep 27 '16 at 21:10