I think this may be because in Python 2, there is a coupling between stdin and stderr (in the C stdlib code) that flushes stdout when you read stdin. This doesn't seem to be required by the C std, but most implementations seem to do it. http://stackoverflow.com/questions/2123528/does-reading-from-stdin-flush-stdout
I think it was a nice feature but I can see problems with it; apps that want this behavior ought to bite the bullet and flush stdout. On Fri, Jan 13, 2012 at 7:34 AM, anatoly techtonik <techto...@gmail.com>wrote: > Posting to python-dev as it is no more relates to the idea of improving > print(). > > > 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 > sys.stdout.write() > > Attached is a test script which is a stripped down version of the recipe > above. > > 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. > > > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > http://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > http://mail.python.org/mailman/options/python-dev/guido%40python.org > > -- --Guido van Rossum (python.org/~guido)
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