CODEWITHSUNDEEP
pythonpython-2.7python-3.x
user422005
user422005

Reputation: 2031

Preparations for python 3: issue warnings?

I am the main guilty of a reasonably large Python package which is used internally in our organisation. I am in the process of preparing the package for Python3; for the code I have control over myself this is quite doable - but there are many scripts "out in the wild" which will break if/when the organisation default interpreter is yanked up to 3.x. The typical situation is as follows:

Some random script I do not have conrol over:

#!/usr/bin/env python    #   By manipulating the environment I will ...
                         #   ... eventually switch this to pick up python3
import company.package   #   This is Python3 safe.

...
print "This - will fail hard"

What I would like to do (if possible) was to insert some global warning directives in the "company.package" code which I control - so that users can get a warning before the global interpreter is yanked up to Python3. Is this possible?

Upvotes: 1

Views: 325

Answers (1)

Stefano Sanfilippo
Stefano Sanfilippo

Reputation: 33046

You can detect when a script is run in Python 2.x and issue an update warning like this:

import warnings
import sys

if sys.version_info < (3,0):
    warnings.warn("company.package will be ported to Python 3 soon. Make sure that your script is Py3k-safe!")

Unfortunately, there is no way to ensure that a Python script will run smoothly in Python3, apart from human inspection based on static analysis (e.g. with 2to3 tool) and/or extensive unit testing.

EDIT: Porting to Python 3 is not only a matter of syntax, but involves module renaming (like urllib, which was split, or cStringIO) and conceptual changes (like the bytearray/string distinction). There is no import magic to check that.

Upvotes: 3

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