What interface is a ‘Popen.stdout’ presenting?

[Ben Finney]

Howdy all,

When I want to wrap a binary stream to provide a text stream, such as
the ‘Popen.stdout’ attribute from a subprocess, I can use
‘io.TextIOWrapper’.

That works on Python 3::

    $ python3
    Python 3.4.4rc1 (default, Dec  7 2015, 11:09:54)
    [GCC 5.3.1 20151205] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import subprocess
    >>> import io
    >>> gnupg_subprocess = subprocess.Popen(["/usr/bin/gpg", "--version"], stdout=subprocess.PIPE)
    >>> gnupg_stdout = io.TextIOWrapper(gnupg_subprocess.stdout)
    >>> type(gnupg_stdout)
    <class '_io.TextIOWrapper'>

but not Python 2::

    $ python2
    Python 2.7.11 (default, Dec  9 2015, 00:29:25)
    [GCC 5.3.1 20151205] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import subprocess
    >>> import io
    >>> gnupg_subprocess = subprocess.Popen(["/usr/bin/gpg", "--version"], stdout=subprocess.PIPE)
    >>> gnupg_stdout = io.TextIOWrapper(gnupg_subprocess.stdout)
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    AttributeError: 'file' object has no attribute 'readable'

I'm trying to write code that, as far as practicable, works unchanged on
Python 2 and Python 3.

How do I wrap an arbitrary byte stream – already opened, such as a
‘Popen.stdout’ attribute – in a text wrapper with a particular encoding?

-- 
 \        “With Lisp or Forth, a master programmer has unlimited power |
  `\     and expressiveness. With Python, even a regular guy can reach |
_o__)                               for the stars.” —Raymond Hettinger |
Ben Finney