[Python-Dev] Backwards incompatible sys.stdout.write() behavior in Python 3 (Was: [Python-ideas] Pythonic buffering in Py3 print())

anatoly techtonik techtonik at gmail.com
Fri Jan 13 16:34:38 CET 2012

Posting to python-dev as it is no more relates to the idea of improving

sys.stdout.write() in Python 3 causes backwards incompatible behavior that
breaks recipe for unbuffered character reading from stdin on Linux -
http://code.activestate.com/recipes/134892/  At first I though that the
problem is in the new print() function, but it appeared that the culprit is

Attached is a test script which is a stripped down version of the recipe

If executed with Python 2, you can see the prompt to press a key (even
though output on Linux is buffered in Python 2).
With Python 3, there is not prompt until you press a key.

Is it a bug or intended behavior? What is the cause of this break?
anatoly t.
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