[issue12760] Add create mode to open()

Roundup Robot added the comment: New changeset ef406c4c6463 by Charles-François Natali in branch 'default': Issue #12760: Add some mising documentation about the new `x` exclusive http://hg.python.org/cpython/rev/ef406c4c6463 -- ___ Python tracker <

[issue12760] Add create mode to open()

Petri Lehtinen added the comment: Shouldn't the documentation of builtin open() (in Doc/library/functions.rst) be updated too? -- nosy: +petri.lehtinen ___ Python tracker ___ _

[issue12760] Add create mode to open()

Charles-François Natali added the comment: Thanks, I've committed your version. -- ___ Python tracker ___ ___ Python-bugs-list mailin

[issue12760] Add create mode to open()

Roundup Robot added the comment: New changeset 8bcbe2dc3835 by Charles-François Natali in branch 'default': Issue #12760: Refer to the new 'x' open mode as "exclusive creation" mode. http://hg.python.org/cpython/rev/8bcbe2dc3835 -- ___ Python tracker

[issue12760] Add create mode to open()

David Townshend added the comment: I've done a bit or rewording in the io docs, but I honestly don't know if this is any better that what you already had! -- Added file: http://bugs.python.org/file24210/x_diff2.patch ___ Python tracker

[issue12760] Add create mode to open()

Charles-François Natali added the comment: Nick suggested to call the new flag "exclusive create" in the doc (and explain in whatsnew that it's based C11 new 'x' flag). Could someone please check the attached patch? My wording sounds really clumsy, so I'd prefer if a native speaker could review

[issue12760] Add create mode to open()

Charles-François Natali added the comment: Committed. David, thanks for the patch! -- resolution: -> fixed stage: commit review -> committed/rejected status: open -> closed ___ Python tracker

[issue12760] Add create mode to open()

Roundup Robot added the comment: New changeset bf609baff4d3 by Charles-François Natali in branch 'default': Issue #12760: Add a create mode to open(). Patch by David Townshend. http://hg.python.org/cpython/rev/bf609baff4d3 -- nosy: +python-dev ___ Py

[issue12760] Add create mode to open()

Charles-François Natali added the comment: > Just a small note: FileExistsError is raised, not exactly OSError, > when the file exists. I've updated the doc accordingly. -- stage: patch review -> commit review ___ Python tracker

[issue12760] Add create mode to open()

Antoine Pitrou added the comment: > Here's a new version of the patch that should address all the comments. Just a small note: FileExistsError is raised, not exactly OSError, when the file exists. -- ___ Python tracker

[issue12760] Add create mode to open()

Charles-François Natali added the comment: Here's a new version of the patch that should address all the comments. -- Added file: http://bugs.python.org/file24179/open_create_x-3.patch ___ Python tracker _

[issue12760] Add create mode to open()

Antoine Pitrou added the comment: I don't think the "created()" method has to be exposed. People can inspect the "mode" attribute if they want to have that information. (besides, the semantics are misleading since a new file opened with "w" has also be created, but created() would return False

[issue12760] Add create mode to open()

Charles-François Natali added the comment: I intend to commit this patch within a couple days (unless anyone objects of course). -- stage: -> patch review ___ Python tracker _

[issue12760] Add create mode to open()

Charles-François Natali added the comment: I've done a small review. -- ___ Python tracker ___ ___ Python-bugs-list mailing list Unsu

[issue12760] Add create mode to open()

Éric Araujo added the comment: > [...] There is slightly more versatility with the opener method, but no more > obviousness > and no less typing. I agree with your opinion. I re-read this report: - Antoine thinks this fills an important use case, namely avoiding race conditions - Amaury then

[issue12760] Add create mode to open()

Devin Jeanpierre added the comment: > Amaury did not suggest to use openat, but the new opener argument to open, > which was especially added for use cases such as the one discussed here: Sorry, yes. Wrong words, same thought. We can implement this using opener, but we could implement this wi

[issue12760] Add create mode to open()

Éric Araujo added the comment: > This is not a "duplicate issue". The openat solution is no easier than the > os.open > solution. Amaury did not suggest to use openat, but the new opener argument to open, which was especially added for use cases such as the one discussed here: ... op

[issue12760] Add create mode to open()

Changes by Chris Rebert : -- nosy: +cvrebert ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python

[issue12760] Add create mode to open()

Antoine Pitrou added the comment: > C11 uses 'x' for this, for what it's worth. > > This is not a "duplicate issue". The openat solution is no easier than > the os.open solution. Ok, let's re-open then. I'm not sold on the feature, but the fact C11 adds a dedicated letter mode for it could b

[issue12760] Add create mode to open()

Devin Jeanpierre added the comment: C11 uses 'x' for this, for what it's worth. This is not a "duplicate issue". The openat solution is no easier than the os.open solution. -- nosy: +Devin Jeanpierre ___ Python tracker

[issue12760] Add create mode to open()

Éric Araujo added the comment: See #13424 for a doc request about this. -- nosy: +eric.araujo ___ Python tracker ___ ___ Python-bugs-

[issue12760] Add create mode to open()

David Townshend added the comment: It is already possible to write a wrapper function that does it: def create(file): fd = os.open(file, os.O_EXCL | os.O_CREAT | os.O_WRONLY) return os.fdopen(fd) The point it not that it can't be done, but that it is not straight forward. The docs sa

[issue12760] Add create mode to open()

Amaury Forgeot d'Arc added the comment: issue12797 would allow things like: def create_exclusive_file(filename): return open(filename, "w", opener=lambda path, mode: os.open(path, mode|os.O_CREAT|os.O_EXCL)) -- ___ Python tracker <

[issue12760] Add create mode to open()

David Townshend added the comment: I see this has been marked as a duplicate of http://bugs.python.org/issue12797. Please explain how this is, since that proposal does not appear to provide the functionality discussed here. -- ___ Python tracker

[issue12760] Add create mode to open()

Changes by Charles-François Natali : -- resolution: -> duplicate status: open -> closed superseder: -> io.FileIO and io.open should support openat ___ Python tracker ___ __

[issue12760] Add create mode to open()

Changes by Arfrever Frehtes Taifersar Arahesis : -- nosy: +Arfrever ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscri

[issue12760] Add create mode to open()

STINNER Victor added the comment: >open(filename, 'w', > fd_opener=lambda path, mode: os.open(path, mode|os.O_CREAT) I prefer open(name, "c"). > it doesn't fill a use case: actually, avoiding race conditions > is an important use case, ... It may help the issue #8604 (and maybe #8

[issue12760] Add create mode to open()

Antoine Pitrou added the comment: > What if we can override the inner call to os.open()? > For example, io.open() could grow an additional argument "fd_opener" > which defaults to the equivalent of os.open. I agree it would be a much better situation than what we have now. --

[issue12760] Add create mode to open()

Amaury Forgeot d'Arc added the comment: > - os.open followed by os.fdopen is easy: it isn't that easy to get > the incantation right (the pure Python open() in _pyio is 70 lines > of code), especially if you want the file object to have the right > "name" attribute What if we can override the i

[issue12760] Add create mode to open()

Antoine Pitrou added the comment: Ah, right. Well I think all arguments against it were quite weak (or even wrong). Let's see: - it's not cross-platform: actually it is (OS_EXCL has been POSIX since at least 1997 (*), and Windows also has it) - os.open followed by os.fdopen is easy: it isn't

[issue12760] Add create mode to open()

Charles-François Natali added the comment: > I haven't seen any discussion on python-dev. Have I missed something? It was on Python-ideas actually: http://mail.python.org/pipermail/python-ideas/2011-August/011183.html -- ___ Python tracker

[issue12760] Add create mode to open()

Antoine Pitrou added the comment: I haven't seen any discussion on python-dev. Have I missed something? -- ___ Python tracker ___ ___

[issue12760] Add create mode to open()

Charles-François Natali added the comment: So, what was the conclusion of the discussion brought up on python-dev? I had a feeling some core devs were opposed to this (I'm personally -0). -- ___ Python tracker ___

[issue12760] Add create mode to open()

David Townshend added the comment: I hope this patch suits you better :-) I've updated the documentation typo (thanks for pointing that out). I've also changed 'c' to 'x', since I think that if there is a convention we should stick to it. I don't think that it matters if the glibc docs say '

[issue12760] Add create mode to open()

STINNER Victor added the comment: > I don't know if it's documented behavior See #12103: it is not documented. -- ___ Python tracker ___ ___

[issue12760] Add create mode to open()

Charles-François Natali added the comment: > Yeah, but I think "exclusively" is quite misleading since it does not > perform any locking of any kind. It might be misleading, but I find it clear enough, and this name has been endorsed by POSIX. Furthermore, there's an added bonus: actually, wi

[issue12760] Add create mode to open()

Antoine Pitrou added the comment: > Well, I'd rather have this flag called 'x', to be consistent with > glibc's fopen(): > > """ >c (since glibc 2.3.3) > Do not make the open operation, or subsequent read and write > operations, thread cancellation points. >

[issue12760] Add create mode to open()

Julian Berman added the comment: A minor documentation error in io.rst line 475 which was changed to: + The *mode* can be ``'c'``, ``'r'``, ``'w'`` or ``'a'`` for reading + (default), writing, or appending. and should have "creating" at the front I assume, like you have it later.

[issue12760] Add create mode to open()

David Townshend added the comment: Changing form 'c' to 'x' is easy enough, and if there is already a convention it makes sense to stick to it. I thought I had done a mercurial diff! I'll try again and resubmit. -- ___ Python tracker

[issue12760] Add create mode to open()

Charles-François Natali added the comment: > The "#ifdef O_EXCL" in the source code is probably very old. Copying a > message I posted on python-ideas: > > O_EXCL is a POSIX standard. It is also supported > under Windows by the _open/_wopen compatibility functions (which we use > for file I/O).

[issue12760] Add create mode to open()

David Townshend added the comment: My aim isn't to add all the commonly used flags, that would be pointless since its already possible using os.open. The aim is to add a missing feature to the builtin open(), i.e. file creation. At the moment open() implements read, write, and append, and c

[issue12760] Add create mode to open()

Antoine Pitrou added the comment: The "#ifdef O_EXCL" in the source code is probably very old. Copying a message I posted on python-ideas: O_EXCL is a POSIX standard. It is also supported under Windows by the _open/_wopen compatibility functions (which we use for file I/O). Probably there are

[issue12760] Add create mode to open()

David Townshend added the comment: It was discussed on python-ideas, but the subject of the thread was actually on shutils.move so it was not really discussed much. I will repost this idea separately. -- ___ Python tracker

[issue12760] Add create mode to open()

Charles-François Natali added the comment: See also issue 12105. A couple downsides: - O_EXCL is not necessarily portable (doesn't work well with NFS, maybe not on Windows?) - O_EXCL is useful, as is O_CLOEXEC: to be consistent, we should also end up adding all other commonly-used flags, which

[issue12760] Add create mode to open()

Benjamin Peterson added the comment: I think this should be brought up on python-ideas or python-dev. -- nosy: +benjamin.peterson ___ Python tracker ___

[issue12760] Add create mode to open()

STINNER Victor added the comment: I'm not sure that O_EXCL is portable (exist on all platforms) because Python source code uses "#ifdef O_EXCL". -- nosy: +haypo ___ Python tracker

[issue12760] Add create mode to open()

New submission from David Townshend : Currently, opening a file with open(file, 'w') overwrites existing files. It would be useful for open() to raise an error when the file exists. This proposal is to add a 'c' mode to open, which has the effect to creating a file and opening it for writing