Any __future__ import for range-xrange incompatibility?

Question

Writting for Python 2, I always use xrange, but it is renamed in Python 3. So I mostly write

if sys.version.startswith('3'):
    zrange = range
else:
    zrange = xrange

and use zrange below. Is there a more graceful solution (without depending on 3rd party package), like from __future__ import unicode_literal hopefully?

Answer 1

No, there is no from __future__ import for this, nor do you need to use a third-party package. Simply catch the name error when xrange is not available:

try:
    zrange = xrange
except NameError:
    zrange = range

There's not really a need to test for versions.

Personally, I'd not make up a new name, just re-use range on Python 2:

try:
    # Python 2
    range = xrange
except NameError:
    # Python 3
    pass

or add xrange in Python 3 as an alias:

try:
    # Python 2
    xrange
except NameError:
    # Python 3
    xrange = range

Re-assigning range in Python 2 only is preferable, since going forward a project is far more likely to drop Python 2 support and focus on Python 3 syntax exclusively than the other way around.

Packages that need to support both Python 2 and Python 3 usually create a compat module to handle bridges like these. See the requests.compat module for example, where they do use a version test only because that limits the number of tests to just the one if.