[Distutils] markers, =?utf-8?Q?<=3D_?=and python 2.7.10

[Donald Stufft]

On July 2, 2015 at 10:34:35 AM, Nick Coghlan (ncoghlan at gmail.com) wrote:
> On 2 July 2015 at 01:37, Donald Stufft wrote:
> > On July 1, 2015 at 12:33:29 AM, Nick Coghlan (ncoghlan at gmail.com) wrote:
> >> From a "how to fix it?" perspective, I think it makes sense to say
> >> that any marker ending in "_version" is compared using PEP 440 version
> >> ordering semantics rather than lexical ordering
> >>
> >> My rationale for that is:
> >>
> >> 1. In the simple X.Y.Z cases, lexical string comparisons and PEP 440
> >> give the same answer
> >> 2. In the more complex cases (like 2.7.10), PEP 440 gives the right
> >> answer, while lexical string comparison fails
> >> 3. Anything handling environment markers already needs to be able to
> >> handle PEP 440 semantics anyway
> >
> > Also agreed. Perhaps the ``_version`` markers should just support the
> > full range of specifiers in PEP 440.
>  
> That's what I was thinking. The one slight difference is that I don't
> believe we'd want any special case handling of pre-releases in
> environment markers - if I have a Python alpha installed, I'd want it
> treated as equivalent to the corresponding final release, since
> constraint checking isn't the same as choosing the "best" version for
> download/installation.
>  
>

Well, even in the case for dependencies we say that a pre-release
should be accepted if it’s installed which would be in that vein
IMO. I agree that it’d be useful to call that out explicitly though.

---  
Donald Stufft  
PGP: 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA