[issue13824] argparse.FileType opens a file and never closes it

Nils Kattenbeck added the comment: A good alternative would be to use pathlib.Path. The only downside would be that one has to manually handle `-` but besides that it solves most problems. Still the fact that file descriptors are kept open should be added as a warning to the docs

[issue13824] argparse.FileType opens a file and never closes it

Change by sebix : -- nosy: +sebix ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue13824] argparse.FileType opens a file and never closes it

Stéphane Wirtel added the comment: Hi, Are you interested to write test cases? They could be useful for the fix. Thank you -- nosy: +matrixise ___ Python tracker ___

[issue13824] argparse.FileType opens a file and never closes it

paul j3 added the comment: While I continue to follow argparse issues, I'm not doing development (with my own repository, etc). I haven't revisited the issue since 2013, and don't know that much more about Python file handling. Occasionally 'FileType' issues come up on StackOverflow,

[issue13824] argparse.FileType opens a file and never closes it

Mitar added the comment: > So it's already possible to do what you describe, simply by doing: I think there is an edge case here if a stdin/stdout is opened? It would get closed at exist from the context, no? So I suggest that a slight extension of what open otherwise returns is returned

[issue13824] argparse.FileType opens a file and never closes it

Rémi Lapeyre added the comment: For information, issue 33927 is related. I removed one of the FileType from json.tool argument parser to work around this behavior (https://github.com/python/cpython/pull/7865/files#diff-e94945dd18482591faf1e294b029a6afR44). If paul.j3 does not have his patch

[issue13824] argparse.FileType opens a file and never closes it

Josh Rosenberg added the comment: Mitar: argparse.FileType's __call__ (which is what "parses" the argument) returns whatever open (aka io.open) returns. Basically, post-parsing, there is nothing about the result of FileType that distinguishes it from a manually opened file (or when '-' is

[issue13824] argparse.FileType opens a file and never closes it

Mitar added the comment: Why not make FileType instance also a context manager, so you could do something like: with arguments.input as f: assert arguments.input is f For backwards compatibility, FileType would open eagerly as now, but it would be closed at exit from context manager.

[issue13824] argparse.FileType opens a file and never closes it

paul j3 added the comment: From http://bugs.python.org/issue14156 argparse.FileType for '-' doesn't work for a mode of 'rb' I learned that 'stdin/out' can be embedded in an 'open' by using the 'fileno()' and 'closefd=False' (so it isn't closed at the end of open). With this, the dummy file

[issue13824] argparse.FileType opens a file and never closes it

paul j3 added the comment: An alternative way to delay the file opening, is to return an instance that has a `filename` attribute, and has an `open` method. This can be compactly added to the `FileContext` that I defined in the previous patch. The `FileContext` provides the `_ostest`

[issue13824] argparse.FileType opens a file and never closes it

paul j3 added the comment: In this patch I implement a FileContext class. It differs from FileType in 2 key areas: - it returns a 'partial(open, filename, ...)' - it wraps '-' (stdin/out) in a dummy context protecting the file from closure. The resulting argument is meant to be used as:

[issue13824] argparse.FileType opens a file and never closes it

Changes by paul j3 ajipa...@gmail.com: -- nosy: +paul.j3 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13824 ___ ___ Python-bugs-list mailing list

[issue13824] argparse.FileType opens a file and never closes it

Steven Bethard steven.beth...@gmail.com added the comment: So I generally agree that FileType is not what you want for anything but quick scripts that can afford to either leave a file open or to close stdin and/or stdout. However, quick scripts are an important use case for argparse, so I

[issue13824] argparse.FileType opens a file and never closes it

Éric Araujo mer...@netwok.org added the comment: Additionally, there is no way to prevent FileType from clobbering an existing file when used with write mode. I think this deserves its own feature request: now that Python 3.3 has an “exclusive create” mode, argparse.FileType could gain

[issue13824] argparse.FileType opens a file and never closes it

Éric Araujo mer...@netwok.org added the comment: s/sure was/sure way/ -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue13824 ___ ___

[issue13824] argparse.FileType opens a file and never closes it

David Layton dmlay...@gmail.com added the comment: Eric, checked that the file exists But then you’d run into race conditions. The only sure was to say if a file can be opened is to open it. I think you misunderstand me. I am NOT suggesting that you open and close the file. I am saying