There are many "gotchas" going from Python 2 to Python 3 - with the change from
"print" to "print()" being by far the most irritating (and the most stringently
enforced by the Python interpreter). There are several IDEs which can highlight
problems and give tips to migrate from Python 2 to Python 3, or to write code
that is compatible for both (in many cases, you can use "try.... except..." -
if the Python 2 code crashes, you simply try to execute the Python 3 statement
thereafter).
It is one of the "features" of the Python language that it is not supposed to
be necessarily backward compatible, but obsolescent features and new features
are announced with very generous transition periods, so that programmers have
sufficient time to update their code. Unfortunately, the long lead time causes
programmers to become lazy, since in practice, obsolescent features are
supported for a long time, thus it is not necessary to update the code
immediately.
For those who are interested: Python is a forward compatible language, where
the statement:
from __future__ import bla
can be used to import the "bla" name; in this way, you can use bla before it
becomes part of the official Python language, which (potentially) saves work in
future code revisions. Obviously it takes an expert to know what __future__
functions there are and whether or not it is worthwhile to use them.
Wilfred
On Tuesday, February 9, 2016 7:00 PM, Philip TAYLOR <p.tay...@rhul.ac.uk>
wrote:
Hallo Khaled --
Khaled Hosny wrote:
> There are many other Python 3 incompatibilities in the code (this
> being Python, you will not encounter them until the code in question
> is actually being executed, which can be deceiving). Regards, Khaled
Yes, I fully appreciate that; all I was trying to do was suggest some
simple zero-effort code that could be added to indicate whether the
system version of Python was compatible with the code as written and
issue an appropriate diagnostic; it was in no way an attempt to re-write
the code such as to make it compatible with both Python 2 and Python 3
other than at the most superficial (lexical) level.
** Phil.
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