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> Agreed. Richard: do you have time to put something together?
> I'm happy to try if you don't.
I'm looking into it.
Unfortunately, it seems that you need to use non-default flags when reopening a shared file. Eg, if the file is currently opened with SH_DENYNO and O_TEMPORARY, then you must reopen it using SH_DENYNO and O_TEMPORARY.
However, I have an initial implementation of os.sopen() which makes the following work:
 import os, tempfile
 FNAME = "foo.txt"
 DATA = "hello bob"
 def opener(name, flag, mode=0o777):
 return os.sopen(name, flag | os.O_TEMPORARY, os.SH_DENYNO, mode)
 with open(FNAME, "w", opener=opener) as f:
 f.write(DATA)
 f.flush()
 with open(FNAME, "r", opener=opener) as f:
 assert f.read() == DATA
 assert not os.path.exists(FNAME)
BTW, Maybe it would be better to add a keyword-only shareflag argument to os.open() rather than add os.sopen().