在 Python 2/3 中打印浮动到 io.StringIO

Question

I'm trying to write a Python program that works in both Python 2.7 and Python 3.*. I have a case where I use StringIO , and according to Python-Future's cheatsheet on StringIO , all I have to to is to use the Python 3-style io module.

The problem is that I'm print ing floats to this StringIO :

from __future__ import print_function
from io import StringIO

with StringIO() as file:
    print(1.0, file=file)

This results in

TypeError: string argument expected, got 'str'

When I replace 1.0 by u"AAAA" (or "AAAA" with unicode_literals enabled), it works fine.

Alternatives I've tried:

• BytesIO . I can't print anymore, because " unicode doesn't support the buffer interface".
• "{:f}".format(...) every float . This is possible, but cumbersome.
• file.write(...) instead of print(..., file=file) . This works, but at this point, I don't see what the use of print() is anymore.

Are there any other options?

Answer 1

This is what I do with this issue:

import sys

if sys.version_info[0] == 2:  # Not named on 2.6
    from __future__ import print_function
    from StringIO import StringIO
else:
    from io import StringIO

This breaks PEP008 by the way ( import s should be at the top of the file), but personally I think it is justified.