Atomic writes to files

[storchaka (Serhiy Storchaka)]

Previous discussion:

Adding atomicwrite in stdlib

This is an useful idiom: Create a (hidden) temporary file with random name. Write data to it. Finally, rename the temporary file to target filename. This idiom is good for: Avoid creating incomplete file Support infile=outfile case for some tools. (e.g. Issue 33927: Allow json.tool to have identical infile and outfile - Python tracker) As far as I know, Python stdlib don’t directly provide this idiom. Users need to implement it by themselves. But implement this idiom both for Unix and Wind…