On Wed, Jan 15, 2014 at 01:22:44PM +0100, "Martin v. Löwis" wrote:

Am 12.01.14 18:39, schrieb Nachshon David Armon:

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I propose that this new version of python use the python 3 unicode model. As the version of python will be fully compatible with both python 2 and with python 3 but NOT necsesarily with all existing code in either. It is designed as a porting tool only.

I don't think that it is possible to write an interpreter that is fully compatible for all it accepts. Would you think that the program

print(repr(2**80).endswith("L"))

is in the subset that should be supported by both Python 2 and Python 3?

IMO Python 2 and 3 do have this part in common when you talk about valid syntax and available methods and functions, but not in terms of behavior. I think a new proposed Python version should simply crash on your example. I'm kind-of playing devil's advocate here because i agree with previous posters that such a Python version is unneccessary with tox and "python2 -3"

Notice that it prints "True" in Python 2 and "False" in Python 3. So if this common-version interpreter *rejects* the above program, which operation (**, repr, endswith) would you want to ban from subset?

Warnings about using certain string methods on repr() might be a neat thing to add to "python -3" or static analysis tools.

Regards, Martin

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