[Python-Dev] Re: NamedTemporaryFile and context managers

Well this works: from tempfile import NamedTemporaryFile import os with NamedTemporaryFile(delete=False) as fp:       fp.write(b'some data')       fp.close()       with open(fp.name, 'rb') as fp2:             data = fp2.read()       os.remove(fp.name) assert data == b'some data' Of course it is theoretically possible that another app will do something to the temporary file between the "fp.close()" and the "open" on the next line, or between closing fp2 and the "os.remove".  Is this a concern? Rob Cliffe On 08/04/2021 22:42, Ethan Furman wrote:

On 4/8/21 1:43 PM, Antoine Pitrou wrote:

...

On Thu, 8 Apr 2021 13:31:26 -0700 Ethan Furman wrote:

...

```python from tempfile import NamedTemporaryFile

with NamedTemporaryFile() as fp:       fp.write(b'some data')       fp.close()  # Windows workaround       fp.open()       data = fp.read()

assert data == 'some_data' ```

The problem is that, even though `fp.open()` is still inside the context manager, the `close()` call deletes the file [2].  To handle this scenario, my proposal is two-fold:

1) stop using the TEMPFILE OS attribute so the OS doesn't delete the file on close 2) add `.open()` to NamedTemporaryFile

Instead, you could add a dedicated `.reopen()`?

The main hurdle is that on Windows we let the OS manage the lifetime of the file, which means that it is deleted as soon as it is closed.  We would need to remove that branch and treat all NamedTemporaryFiles the same.

We could add reopen(), but since close() is already there... although I do like the name of `reopen`.

-- ~Ethan~ _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-leave@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/2DGIFUS6... Code of Conduct: http://python.org/psf/codeofconduct/