In issue14243 [1] there are two issues being tracked:
- the difference in opening shared files between posix and Windows
- the behavior of closing the underlying file in the middle of
NamedTemporaryFile's context management
I'd like to address and get feedback on the context management issue.
```python
from tempfile import NamedTemporaryFile
with NamedTemporaryFile() as fp:
fp.write(b'some data')
fp = open(fp.name())
data = fp.read()
assert data == 'some_data'
```
Occasionally, it is desirable to close and reopen the temporary file in order to read the contents (there are OSes that
cannot open a temp file for reading while it is still open for writing). This would look like:
```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
A possible side effect of (1) is that temp files may accumulate if the interpreter crashes, but given the
file-management abilities in today's software that seems like a minor annoyance at most.
The backwards compatibility issue of (1) is that the file is no longer deleted after a manual `close()` -- but why one
would call close() and then stay inside the CM, outside of testing, I cannot fathom. [3]
So, opinions on modifying NamedTemporaryFile to not delete on close() if inside
a CM, and add open() ?
--
~Ethan~
[1] https://bugs.python.org/issue14243
[2] plus, the `.open()` doesn't yet exist
[3] feel free to educate me :-)
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