"python -3" not working as expected

Thorsten Kampe thorsten at thorstenkampe.de
Thu Jan 8 22:39:18 CET 2009


* Marc 'BlackJack' Rintsch (8 Jan 2009 16:26:55 GMT)
> On Thu, 08 Jan 2009 16:38:53 +0100, Thorsten Kampe wrote:
> > [Python 2.6.1]
> > 
> > to test existing Python code, I ran "python -3" ("warn about Python 3.x
> > incompatibilities") against a test file that only contains "print
> > 'test'".
> > 
> > Unfortunately I saw no warnings about print becoming a function in
> > Python 3 ("print()"). Where is the problem?
> 
> There is no problem.  ``print``\s are handled fine by the 2to3.py 
> script.  The option warns about stuff that is not easily automatically 
> converted.

There /is/ obviously a problem: the Python command line help[1] and the 
"Porting To Python 3.0" section of "What’s New In Python 3.0" from Guido 
van Rossum are misleading (if not to say wrong):

"""
For porting existing [...] code to Python 3.0, the best strategy is the 
following:
[...]
2. [...] Turn on the -3 command line switch. This enables warnings about 
features that will be removed (or change) in 3.0.[...]
3. Run the 2to3 source-to-source translator [...]
"""

Thorsten
[1] "-3     : warn about Python 3.x incompatibilities"



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