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Re: [Python] RE: How to safely maintain a status file

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On 13/07/2012 19:28, Hans Mulder wrote:
> On 13/07/12 19:59:59, Prasad, Ramit wrote:
>
>> I lean slightly towards the POSIX handling with the addition that
>> any additional write should throw an error. You are now saving to
>> a file that will not exist the moment you close it and that is
>> probably not expected.
>
Strictly speaking, the file does exist, it's just that there are no
names referring to it. When any handles to it are also closed, the file
_can_ truly be deleted.

As has been said before, in the *nix world, "unlink" _doesn't_ delete
a file, it deletes a name.

> I'd say: it depends.
>
> If the amount of data your script needs to process does not fit
> in RAM, then you may want to write some of it to a temporary file.
> On a Posix system, it's entirely normal to unlink() a temp file
> first thing after you've created it.  The expectation is that the
> file will continue to exists, and be writeable, until you close it.
>
> In fact, there's a function in the standard library named
> tempfile.TemporaryFile that does exactly that: create a file
> and unlink it immediately.  This function would be useless
> if you couldn't write to your temporary file.
>
It's possible to create a temporary file even in Windows.

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Re: How to safely maintain a status file Laszlo Nagy <gandalf@shopzeus.com> - 2012-07-12 14:30 +0200
  Re: How to safely maintain a status file Hans Mulder <hansmu@xs4all.nl> - 2012-07-12 15:19 +0200
    Re: How to safely maintain a status file Laszlo Nagy <gandalf@shopzeus.com> - 2012-07-12 19:43 +0200
    Re: How to safely maintain a status file Christian Heimes <lists@cheimes.de> - 2012-07-12 20:39 +0200
      Re: How to safely maintain a status file Rick Johnson <rantingrickjohnson@gmail.com> - 2012-07-12 18:20 -0700
        Re: How to safely maintain a status file Chris Angelico <rosuav@gmail.com> - 2012-07-13 12:12 +1000
          Re: How to safely maintain a status file Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-13 03:13 +0000
            Re: How to safely maintain a status file Gene Heskett <gheskett@wdtv.com> - 2012-07-12 23:49 -0400
              Re: How to safely maintain a status file Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-13 04:21 +0000
            Re: How to safely maintain a status file rantingrickjohnson@gmail.com - 2012-07-12 21:26 -0700
              Re: How to safely maintain a status file Chris Angelico <rosuav@gmail.com> - 2012-07-13 16:02 +1000
              Re: How to safely maintain a status file Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-13 07:14 +0000
                Re: How to safely maintain a status file Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-13 13:29 -0400
              RE: How to safely maintain a status file "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-07-13 16:00 +0000
              Re: [Python] RE: How to safely maintain a status file Chris Gonnerman <chris@gonnerman.org> - 2012-07-13 12:27 -0500
              RE: [Python] RE: How to safely maintain a status file "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-07-13 17:59 +0000
                Re: [Python] RE: How to safely maintain a status file Hans Mulder <hansmu@xs4all.nl> - 2012-07-13 20:28 +0200
                Re: [Python] RE: How to safely maintain a status file MRAB <python@mrabarnett.plus.com> - 2012-07-13 20:57 +0100
                Re: [Python] RE: How to safely maintain a status file Christian Heimes <lists@cheimes.de> - 2012-07-13 22:21 +0200
              Re: [Python] RE: How to safely maintain a status file Chris Angelico <rosuav@gmail.com> - 2012-07-14 04:19 +1000
              RE: How to safely maintain a status file Chris Gonnerman <chris@gonnerman.org> - 2012-07-13 15:15 -0500
                Re: How to safely maintain a status file Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-14 01:53 +0000

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