Tim Golden wrote:
Joe Strout wrote:
A follow-up question here... is it really necessary to close things
like files in Python? I've been slumming it in the REALbasic
community for the last decade, where you generally don't worry about
such things, as any object that represents something "open" will
automatically "close" itself when it dies (and since a closed object
in those cases is useless, I'd rather not have it around after it's
closed anyway). Is the same true in Python, or do we need to
explicitly close things?
Implementation dependent. (Because it depends on what kind
of garbage collection or object finalisation happens). Like
most people, I imagine, in ad-hoc code I'll just do things like:
<code
import csv
writer = csv.writer (open ("data.csv", "wb"))
writer.writerow (['blah', blah'])
</code>
If I exit the interpreter here, I'm pretty much safe.
But if I add os.startfile ("data.csv"), I'll likely
get nothing or a file lock.
I believe that in other implementations -- Jython,
for example -- you cannot rely on the file closing
itself.
The file will be closed automatically when the file object is
garbage-collected.
CPython uses reference-counting, so the file object is garbage-collected
as soon as there are no references to it.
Jython (and IronPython?) are garbage-collected in the background, so the
file object is garbage-collected at some point (and you don't know when
that will be!) when there are no longer any references to it.
In general in posting public code, especially to
newcomers, I make the effort to use a try-finally
or a with statement.
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