Python 2 and Python 3 dual development

Question

I\'m just starting a new Python project, and ideally I\'d like to offer Python 2 and 3 support from the start, with minimal developmental overhead. My question is, what is t

Answer 1

My personal experience has been that it's easier to write code that works unchanged in both Python 2 and 3, rather than rely on 2to3/3to2 scripts which often can't quite get the translation right.

Maybe my situation is unusual as I'm doing lots with byte types and 2to3 has a hard task converting these, but the convenience of having one code base outweighs the nastiness of having a few hacks in the code.

As a concrete example, my bitstring module was an early convert to Python 3 and the same code is used for Python 2.6/2.7/3.x. The source is over 4000 lines of code and this is this bit I needed to get it to work for the different major versions:

# For Python 2.x/ 3.x coexistence
# Yes this is very very hacky.
try:
    xrange
    for i in range(256):
        BYTE_REVERSAL_DICT[i] = chr(int("{0:08b}".format(i)[::-1], 2))
except NameError:
    for i in range(256):
        BYTE_REVERSAL_DICT[i] = bytes([int("{0:08b}".format(i)[::-1], 2)])
    from io import IOBase as file
    xrange = range
    basestring = str

OK, that's not pretty, but it means that I can write 99% of the code in good Python 2 style and all the unit tests still pass for the same code in Python 3. This route isn't for everyone, but it is an option to consider.