Prefer using py3 compatible syntax over 2.x-only syntax

[ermo]

If one day we decide to port flimage to python3, it will probably make the porting process less painful if we have the foresight to begin adopting forward compatible py2.x syntax and idioms.

A simple example would be print() and string substitution:

# forward compatible from 2.6 -> 3.x (note the extra parentheses)
print("There are %s types of people in the world; those who understand binary and those who don't." %
      (bin(2)[2:]))

Additional resources:

• http://wiki.python.org/moin/PortingPythonToPy3k
• http://python3porting.com/
• http://lucumr.pocoo.org/2011/1/22/forwards-compatible-python/

[johnsonm]

LWN on The future of Python 2

[johnsonm]

We should care about compatibility only with py3.latest (at whatever time we really care) and they have been re-adding some py2 features to make porting easier so I don't want to care about compatibility with py3.early and make gratuitous changes.

[ermo]

Objectively, I cannot find fault with that point of view.

I suppose the fact that, subjectively, I genuinely prefer coding in Py3 over Py2 does tend to color my perception of the importance of this particular issue. Yet, "Python 3 just feels better to me" doesn't strike me as being particularly likely to be a successful line of argument with you... g