[issue26290] fileinput and 'for line in sys.stdin' do strange mockery of input buffering

[Josh Rosenberg]

Josh Rosenberg <shadowranger+python at gmail.com> added the comment:

For those who find this in the future, the simplest workaround for the:

for line in sys.stdin:

issue on Python 2 is to replace it with:

for line in iter(sys.stdin.readline, ''):

The problem is caused by the way file.__next__'s buffering behaves, but file.readline doesn't use that code (it delegates to either fgets or a loop over getc/getc_unlocked that never overbuffers beyond the newline). Two-arg iter lets you make an iterator that calls readline each time you want a line, and considers a return of '' (which is what readline returns when you hit EOF) to terminate iteration.

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nosy: +josh.r

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue26290>
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