Import "izip" for different versions of Python

Question

A common idiom that I use for Python2-Python3 compatibility is:

try:
    from itertools import izip
except ImportError:  #python3.x
    izip = zip

However, a comment on one of my Stack Overflow answers implies that there may be a better way. Is there a more clean way to accomplish this?

Answer 1

Not sure this is really an answer, or I should elaborate on my comment, and in hindsight probably not even a very good comment anyway, but:

Firstly, you can just simplify it to:

try:
    from itertools import izip as zip
except ImportError: # will be 3.x series
    pass

What I was thinking about was:

From 2.6 you can use as per the docs:

from future_builtins import map # or zip or filter

You do however then have the same problem of ImportError - so:

try:
    from future_builtins import zip
except ImportError: # not 2.6+ or is 3.x
    try:
        from itertools import izip as zip # < 2.5 or 3.x
    except ImportError:
        pass

The advantage of using future_builtin is that it's in effect a bit more "explicit" as to intended behaviour of the module, supported by the language syntax, and possibly recognised by tools. For instance, I'm not 100% sure, but believe that the 2to3 tool will re-write zip correctly as list(zip(... in this case, while a plain zip = izip may not be... But that's something that needs looking in to.

Updated - also in the docs:

The 2to3 tool that ports Python 2 code to Python 3 will recognize this usage and leave the new builtins alone.

Answer 2

If you are trying to make Python 2.x code compatible with Python 3.x you should look at six:

http://pythonhosted.org/six/#module-six.moves

Answer 3

This is roughly twice as fast as using a try/except:

import itertools
zip = getattr(itertools, 'izip', zip)