[Distutils] [Python-Dev] [Python-checkins] peps: PEP 426: replace implied 'version starts with' with new ~= operator

Daniel Holth dholth at gmail.com
Tue Feb 26 17:07:52 CET 2013

On Tue, Feb 26, 2013 at 11:01 AM, Donald Stufft <donald.stufft at gmail.com>wrote:

> On Tuesday, February 26, 2013 at 10:10 AM, Nick Coghlan wrote:
> Remember, part of the goals of both PEP 386 and PEP 426 is to tighten
> up cases where setuptools is considered too permissive, because it's
> guessing in the face of ambiguity. "Trailing zeroes should be
> considered implied" when comparing versions is one such guess.
> It goes against the common usage in the Python community.
> * 135869 total releases
> * 66528 total releases that have at least 3 version levels (A.B.C)
> * 20244 total releases that have at least 3 version levels where A.B and
>   A.B.0 appear to be equivalent[1].
> * 86 total releases using at least 3 version levels where A.B and A.B.0
> appear
>   to be different[2].
> Would break the assumptions made in ~30% of the releases using at least 3
> version levels, or 15% of all releases. Furthermore A.B == A.B.0 being
> equivalent is a matter of opinion with no clear answer. I would be inclined
> to say that not breaking it for the 15% of all releases is a greater net
> benefit here then anyones notion of "right" unless there is a clear
> benefit.
> For what it's worth, the implementation of PEP386 treats them as equal as
> well,
> choosing to pad the shorter one out to whatever the requisite number of 0's
> is required to make the number of components equal.
> On a tangential note PyPI should probably not be allowing you to upload
> both
> a A.B and an A.B.0, or at the very least if we want PyPI to continue
> allowing
> it then we need to be explicit about how that should be handled in either
> scheme.

With "prefix equals" would the following evaluate to true?

1.4 == 1 == 1.3.1
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