[New-bugs-announce] [issue24402] input() uses sys.__stdout__ instead of sys.stdout for prompt

[Keita Kita]

New submission from Keita Kita:

On Python 3.4, input() does not use wrapped sys.stdout. For example, the following script should print "Wrapped stdout" by print() and input() because sys.stdout is replaced with Writer object.

--------
import io
import sys


class Writer:
    def __getattr__(self, name):
        return getattr(sys.__stdout__, name)

    def write(self, data):
        if data != '\n':
            sys.__stdout__.write('Wrapped stdout\n')

    def fileno():
        raise OSError()


sys.stdout = Writer()

print('print')
input('input')
------

But the script does not print "Wrapped stdout" as prompt of input(). The script
prints the following.

-----
Wrapped stdout
input
----

Although, when sys.stdin is also wrapped, input() will use sys.stdout for prompt. For example, the following script prints "Wrapped stdout" by print() and input().

----
import io
import sys


class Writer:
    def __getattr__(self, name):
        return getattr(sys.__stdout__, name)

    def write(self, data):
        if data != '\n':
            sys.__stdout__.write('Wrapped stdout\n')

    def fileno():
        raise OSError()


class Reader:
    def __getattr__(self, name):
        return getattr(sys.__stdin__, name)

    def read(self, size):
        return sys.__stdin__.read(size)

    def fileno():
        raise OSError()


sys.stdout = Writer()
sys.stdin = Reader()

print('print')
input('input')
----

The script prints the following.

-----
Wrapped stdout
Wrapped stdout
----

----------
components: Interpreter Core
messages: 244949
nosy: Keita Kita
priority: normal
severity: normal
status: open
title: input() uses sys.__stdout__ instead of sys.stdout for prompt
type: behavior
versions: Python 3.4

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue24402>
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