On 9 June 2012 10:55, Nick Coghlan <ncoghlan@gmail.com> wrote:
So, after much digging, it appears the *right* way to replace a standard stream in Python 3 after application start is to do the following:
sys.stdin = open(sys.stdin.fileno(), 'r', <new settings>) sys.stdout = open(sys.stdout.fileno(), 'w', <new settings>) sys.stderr = open(sys.stderr.fileno(), 'w', <new settings>)
Ditto for the other standard streams. It seems it already *is* as simple as with any other file, we just collectively forgot about:
One minor point - if sys.stdout is redirected, *and* you have already written to sys.stdout, this resets the file pointer. With test.py as import sys print("Hello!") sys.stdout = open(sys.stdout.fileno(), 'w', encoding='utf-8') print("Hello!") test.py >a gives one line in a, not two (tested on Windows, Unix may be different). And changing to "a" doesn't resolve this... Of course, the actual use case is to change the encoding before anything is written - so maybe a small note saying "don't do this" is enough. But it's worth mentioning before we get the bug report saying "Python lost my data" :-) Paul.