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Re: Will file be closed automatically in a "for ... in open..." statement?

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From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Subject Re: Will file be closed automatically in a "for ... in open..." statement?
Date Wed, 17 Feb 2016 15:36:53 +1100
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On Wed, Feb 17, 2016 at 3:04 PM,  <jfong@ms4.hinet.net> wrote:
> Thanks for these detailed explanation. Both statements will close file automatically sooner or later and, when considering the exceptions, "with" is better. Hope my understanding is right.
>
> But, just curious, how do you know the "for" will do it? I can't find any document about it from every sources I know. Very depressed:-(
>

It's not the 'for' loop that does it. The for loop is kinda like this:

_temp = open("foo.txt")
_temp.read() # do stuff, do stuff
_temp = None

When you stop holding onto an object, Python can get rid of it. When
that happens is not promised, though - and if you have a reference
loop, it might hang around for a long time. But when a file object is
disposed of, the underlying file will get closed.

ChrisA

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Thread

Will file be closed automatically in a "for ... in open..." statement? jfong@ms4.hinet.net - 2016-02-16 00:39 -0800
  Re: Will file be closed automatically in a "for ... in open..." statement? Chris Angelico <rosuav@gmail.com> - 2016-02-16 20:16 +1100
  Re: Will file be closed automatically in a "for ... in open..." statement? Cameron Simpson <cs@zip.com.au> - 2016-02-16 20:24 +1100
  Re: Will file be closed automatically in a "for ... in open..." statement? Terry Reedy <tjreedy@udel.edu> - 2016-02-16 04:41 -0500
  Re: Will file be closed automatically in a "for ... in open..." statement? jfong@ms4.hinet.net - 2016-02-16 20:04 -0800
    Re: Will file be closed automatically in a "for ... in open..." statement? Chris Angelico <rosuav@gmail.com> - 2016-02-17 15:36 +1100
    Re: Will file be closed automatically in a "for ... in open..." statement? Raspberry Aether <raspberryaether@e-s.invalid> - 2016-02-16 23:42 -0500
    Re: Will file be closed automatically in a "for ... in open..." statement? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-02-17 16:51 +1100
      Re: Will file be closed automatically in a "for ... in open..." statement? Tim Chase <python.list@tim.thechases.com> - 2016-02-17 20:32 -0600
  Re: Will file be closed automatically in a "for ... in open..." statement? jfong@ms4.hinet.net - 2016-02-17 17:29 -0800
    Re: Will file be closed automatically in a "for ... in open..." statement? Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-02-18 02:05 +0000
  Re: Will file be closed automatically in a "for ... in open..." statement? Jeremy Leonard <jrmy.lnrd@gmail.com> - 2016-02-18 10:02 -0800

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