[Python-Dev] repeated keyword arguments (original) (raw)

Guido van Rossum guido at python.org
Sat Jun 28 01:03:45 CEST 2008

On Fri, Jun 27, 2008 at 2:54 PM, Fred Drake <fdrake at acm.org> wrote:

On Jun 27, 2008, at 5:23 PM, Benjamin Peterson wrote:

I think code that uses this is probably already quite broken in some fundamental way and putting the fix in 2.5 isn't much of a risk. I suspect the risk has more to do with breaking something else in Python than in breaking 3rd-party code in this case. I think it should be fixed for 2.5 as well, myself.

Let me clarify why I want to be so careful with this.

If there is code that was expected to work but due to a bug in our code raises an exception, it's generally safe to fix this: people who ran into the issue found that their code didn't work, used a work-around, and that's the end of the story.

But if there is code that was expected to break but due to a bug in our code doesn't raise an exception, people can very well have harmless occurrences of such code, and never noticed. Maybe their code is "broken" in the sense that it doesn't produce the correct result, but it may well be in a "don't care" way -- but if an upgrade suddenly starts raising the exception, they are likely to get unhandled exceptions where before they had none. This is particularly annoying when the author of the program that breaks is not the user of the program, to whose machine the upgrade was applied.

In such cases I think it's better not to introduce new exceptions in point-point releases.

-- --Guido van Rossum (home page: http://www.python.org/~guido/)

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