[Python-Dev] draft pep: backwards compatibility

Benjamin Peterson benjamin at python.org
Fri Jun 19 15:56:12 CEST 2009

2009/6/19 Antoine Pitrou <solipsis at pitrou.net>:
> Benjamin Peterson <benjamin <at> python.org> writes:
>> This policy applys to all public APIs.
> applies?

Yes, thanks.
>> * The behavior of an API *must* not change between any two consecutive
>> releases.
>> * A feature cannot be removed without notice between any two consecutive
>>   releases.
> By induction, this would mean no API could change and no feature could be
> removed without notice between any N consecutive releases. Do you really mean
> it?

No, I'll reword.

>> * Addition of a feature which breaks 3rd party libraries or applications
>> should
>>   have a large benefit to breakage ratio, and/or the incompatibility should
>> be
>>   trival to fix in broken code.
> There is always the possibility that a new feature breaks existing code, for
> example because it relies on a similarly named attribute, or on some obscure
> internal condition. I think this should be qualified so that it only applies
> when e.g. a fair number of third-party apps or libraries are broken.

I add a few examples.


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