[Distutils] Finishing PEP 345

["Martin v. Löwis"]

> Ok maybe that would be the solution indeed: if we add a ~= symbol
> that compares ranges, we could make it the default operator. e.g.:
> 
>     Requires-Python: 3.1
> 
> would mean
> 
>    Requires-Python: ~=3.1
> 
> wich would be equal to:
> 
>    Requires-Python: >=3.1,<3.2
> 
> 
> Then == would compare precise versions.
> 
> 
> How does that sounds ?

Maybe it's bike-shedding, but yes, I would like to have a separate
operator for this range matching. So it would be fine with me.

>> Where is that specified? I can't find it in the PEP.
> 
> It is not specified like this, but the examples in PEP 386 indicates
> that b4 is a marker for a beta pre-release. And that "a" , "b" , "c"
> are post-release markers.

I agree that PEP 386 specifies sufficiently that 3.6b4 < 3.6. However,
I was wondering where it is specified that your == operator is
equivalent to a range starting at the value. If it was "wildcard
matching" (which I assume it was), I would have expect that "==3.6"
means "matches 3\.6.*" (in re syntax), so 3.6b4 would match.

> Yes. That's quite a problem. I am wondering if we should introduce
> a specific operator to include/exclude pre and post releases.
> 
> The use case I can see would be to be able :
> - to exclude pre-releases and post-releases (defaut behaviour)
> - to include one of them, or both

It may be useful, but I would wait for user demand. In the end, if
you install a prerelease, and then find that something breaks, it's
really "your fault".

Regards,
Martin