I usually use:
f = open(path,'w')
print >> f, string
f.close()
However, I saw in other's codes:
print >> open(path,'w'), string
also works well.
So, we don't have to close the file if it is opened with 'print'?
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Jonathan Leffler
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bayesrule
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It doesn't matter how you use the result of `open()`; it is still an open file object whatever the context. – Martijn Pieters Apr 18 '13 at 16:26
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4Always use `with`. See the PEP343 for more informations. – aldeb Apr 18 '13 at 16:27
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@MartijnPieters so the second usage is wrong? – bayesrule Apr 18 '13 at 16:29
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Yes. The second usage is wrong. – aldeb Apr 18 '13 at 16:30
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@HaoLiu: What I am saying is that using `print >>` doesn't differ from using the open file in any other context. See the linked duplicate post for details on what happens with open files that you don't explicitly close. – Martijn Pieters Apr 18 '13 at 16:30
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1This is a distinct question because it is asking about whether there is an exception for the print-statement. – Raymond Hettinger Apr 18 '13 at 16:33
1 Answers
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Yes, you still need to close the file. There is no difference with print.
Closing the file will flush the data to disk and free the file handle.
In CPython, the system will do this for you when the reference count for f drops to zero. In PyPy, IronPython, and Jython, you would need to wait for the garbage collector to run (for automatic file closing). Rather that adopt the fragile practice of relying on automatic closing by the memory manager, the preferred practice is for you to control the closing of the file.
Since explicit closing of files is a best practice, Python has provided a context manager for file objects that makes it very easy:
with open(path, 'w') as f:
print >> f, string
This will close your file when you leave the body of the with-statement.
Raymond Hettinger
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