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Groups > comp.lang.python > #45053
| Date | 2013-05-09 19:34 +0100 |
|---|---|
| From | MRAB <python@mrabarnett.plus.com> |
| Subject | Re: object.enable() anti-pattern |
| References | <518a123c$0$11094$c3e8da3@news.astraweb.com> <Z1Eit.289$oB7.283@newsfe02.iad> <518b32ef$0$11120$c3e8da3@news.astraweb.com> <roy-8428A6.09074209052013@news.panix.com> <518be931$0$29997$c3e8da3$5496439d@news.astraweb.com> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.1501.1368124461.3114.python-list@python.org> (permalink) |
On 09/05/2013 19:21, Steven D'Aprano wrote:
> On Thu, 09 May 2013 09:07:42 -0400, Roy Smith wrote:
>
>> In article <518b32ef$0$11120$c3e8da3@news.astraweb.com>,
>> Steven D'Aprano <steve+comp.lang.python@pearwood.info> wrote:
>>
>>> There is no sensible use-case for creating a file without opening it.
>>
>> Sure there is. Sometimes just creating the name in the file system is
>> all you want to do. That's why, for example, the unix "touch" command
>> exists.
>
> Since I neglected to make it clear above that I was still talking about
> file objects, rather than files on disk, I take responsibility for this
> misunderstanding. I thought that since I kept talking about file
> *objects* and *constructors*, people would understand that I was talking
> about in-memory objects rather than on-disk files. Mea culpa.
>
> So, let me rephrase that sentence, and hopefully clear up any further
> misunderstandings.
>
> There is no sensible use-case for creating a file OBJECT unless it
> initially wraps an open file pointer.
>
You might want to do this:
f = File(path)
if f.exists():
...
This would be an alternative to:
if os.path.exists(path):
...
> This principle doesn't just apply to OOP languages. The standard C I/O
> library doesn't support creating a file descriptor unless it is a file
> descriptor to an open file. open() has the semantics:
>
> "It shall create an open file description that refers to a file and a
> file descriptor that refers to that open file description."
>
> http://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html
>
> and there is no corresponding function to create a *closed* file
> description. (Because such a thing would be pointless.)
>
[snip]
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object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-08 08:52 +0000
Re: object.enable() anti-pattern Christian Heimes <christian@python.org> - 2013-05-08 11:51 +0200
Re: object.enable() anti-pattern Robert Kern <robert.kern@gmail.com> - 2013-05-08 11:13 +0100
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-08 12:30 +0000
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-08 09:17 -0400
Re: object.enable() anti-pattern Duncan Booth <duncan.booth@invalid.invalid> - 2013-05-08 14:27 +0000
Re: object.enable() anti-pattern Dan Sommers <dan@tombstonezero.net> - 2013-05-09 02:38 +0000
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-09 05:37 +0000
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-09 15:52 +1000
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-09 03:12 +0000
Re: object.enable() anti-pattern Dan Sommers <dan@tombstonezero.net> - 2013-05-09 02:42 +0000
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-09 05:23 +0000
Re: object.enable() anti-pattern Terry Jan Reedy <tjreedy@udel.edu> - 2013-05-09 02:41 -0400
Re: object.enable() anti-pattern Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2013-05-09 19:54 +1200
Re: object.enable() anti-pattern Cameron Simpson <cs@zip.com.au> - 2013-05-09 18:23 +1000
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-09 11:30 +0000
Re: object.enable() anti-pattern Cameron Simpson <cs@zip.com.au> - 2013-05-10 09:36 +1000
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-10 05:00 +0000
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-10 01:50 -0400
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-10 09:47 +0000
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-10 09:22 -0400
Re: object.enable() anti-pattern Cameron Simpson <cs@zip.com.au> - 2013-05-11 08:25 +1000
Re: object.enable() anti-pattern Mark Janssen <dreamingforward@gmail.com> - 2013-05-10 20:16 -0700
Re: object.enable() anti-pattern Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2013-05-11 06:21 +0200
Re: object.enable() anti-pattern Mark Janssen <dreamingforward@gmail.com> - 2013-05-10 21:00 -0700
Re: object.enable() anti-pattern Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-05-11 15:04 -0400
Re: object.enable() anti-pattern Greg Ewing <greg.ewing@canterbury.ac.nz> - 2013-05-10 10:56 +1200
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-09 09:07 -0400
Re: object.enable() anti-pattern Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-05-09 14:51 +0100
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-09 18:21 +0000
Re: object.enable() anti-pattern MRAB <python@mrabarnett.plus.com> - 2013-05-09 19:34 +0100
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-10 02:30 +0000
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-09 23:09 -0400
Re: object.enable() anti-pattern Mark Janssen <dreamingforward@gmail.com> - 2013-05-09 20:19 -0700
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-10 13:46 +1000
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-10 05:03 +0000
Re: object.enable() anti-pattern Dan Sommers <dan@tombstonezero.net> - 2013-05-10 06:22 +0000
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-10 11:00 +0000
Re: object.enable() anti-pattern Robert Kern <robert.kern@gmail.com> - 2013-05-10 13:19 +0100
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-10 10:01 -0400
Re: object.enable() anti-pattern Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-05-10 15:29 +0100
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-10 10:37 -0400
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-11 00:46 +1000
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-10 10:54 -0400
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-11 01:09 +1000
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-10 11:21 -0400
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-11 01:44 +1000
Re: object.enable() anti-pattern Robert Kern <robert.kern@gmail.com> - 2013-05-10 16:33 +0100
Re: object.enable() anti-pattern Serhiy Storchaka <storchaka@gmail.com> - 2013-05-10 18:44 +0300
Re: object.enable() anti-pattern André Malo <ndparker@gmail.com> - 2013-05-11 17:33 +0200
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-12 02:04 +1000
Re: object.enable() anti-pattern Robert Kern <robert.kern@gmail.com> - 2013-05-10 18:20 +0100
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-11 07:51 +0000
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-11 09:31 -0400
Re: object.enable() anti-pattern Robert Kern <robert.kern@gmail.com> - 2013-05-11 20:55 +0100
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-12 08:39 +1000
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-11 03:24 +1000
Re: object.enable() anti-pattern Mark Janssen <dreamingforward@gmail.com> - 2013-05-10 19:43 -0700
Re: object.enable() anti-pattern Wayne Werner <wayne@waynewerner.com> - 2013-05-12 11:48 -0500
Re: object.enable() anti-pattern Terry Jan Reedy <tjreedy@udel.edu> - 2013-05-12 16:23 -0400
Re: object.enable() anti-pattern Mark Janssen <dreamingforward@gmail.com> - 2013-05-09 20:51 -0700
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-10 13:08 +1000
Re: object.enable() anti-pattern roy@panix.com (Roy Smith) - 2013-05-09 14:59 -0400
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-10 07:55 +1000
Re: object.enable() anti-pattern Nobody <nobody@nowhere.com> - 2013-05-10 17:59 +0100
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-10 13:32 -0400
Re: object.enable() anti-pattern Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-05-11 15:24 -0400
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-11 07:05 +0000
Re: object.enable() anti-pattern Mark Janssen <dreamingforward@gmail.com> - 2013-05-08 19:53 -0700
Re: object.enable() anti-pattern Mark Janssen <dreamingforward@gmail.com> - 2013-05-08 19:56 -0700
Re: object.enable() anti-pattern Wayne Werner <wayne@waynewerner.com> - 2013-05-09 06:08 -0500
Re: object.enable() anti-pattern Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-05-09 11:51 +0000
Re: object.enable() anti-pattern Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2013-05-10 11:43 +1200
Re: object.enable() anti-pattern Michael Speer <knomenet@gmail.com> - 2013-05-09 20:18 -0400
Re: object.enable() anti-pattern Roy Smith <roy@panix.com> - 2013-05-09 20:50 -0400
Re: object.enable() anti-pattern Wayne Werner <wayne@waynewerner.com> - 2013-05-12 12:14 -0500
Re: object.enable() anti-pattern Terry Jan Reedy <tjreedy@udel.edu> - 2013-05-12 16:03 -0400
Re: object.enable() anti-pattern Greg Ewing <greg.ewing@canterbury.ac.nz> - 2013-05-13 11:18 +1200
Re: object.enable() anti-pattern Fábio Santos <fabiosantosart@gmail.com> - 2013-05-13 07:32 +0100
Re: object.enable() anti-pattern Chris Angelico <rosuav@gmail.com> - 2013-05-13 17:36 +1000
Re: object.enable() anti-pattern Fábio Santos <fabiosantosart@gmail.com> - 2013-05-13 09:09 +0100
Re: object.enable() anti-pattern Wayne Werner <wayne@waynewerner.com> - 2013-05-13 08:15 -0500
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