[Distutils] distlib locator compares reasonably well with pip's PackageFinder

[PJ Eby]

On Sat, Oct 27, 2012 at 5:57 AM, Vinay Sajip <vinay_sajip at yahoo.co.uk> wrote:
> PJ Eby <pje <at> telecommunity.com> writes:
>
>>
>> Just as an FYI, are you aware of the #egg=projname-version tagging
>> convention currently in use for such links?
>
> I wasn't - thanks - still new to this game :-) In the cases I was referring to,
> the fragment looks like #egg=projname-dev.

"dev" is the version, actually.  It's a perfectly valid version to
setuptools, and parses as a version that's below any commonly-used
version.  This lets people specify "==dev" to target an in-development
version for installation -- usually manually, but sometimes
automatically.  One might specify, for example "foobar>2.0,==dev" to
tell setuptools that if you can't find a released version >2.0, then
an in-development version is acceptable.


> I'm not sure if we should, as default behaviour, identify such archives as
> potential downloads,

If they're using a "dev" version, then such a link is automatically
lower-precedence than anything else already, due to it being the
lowest available version.(Newer tools could treat it as 0dev or
whatever the official translation/suggestion is.)  In addition, it
denotes a "non-stable" version, so if the tool allows one to
prioritize stable versions, it'll be eliminated as a candidate anyway
in that case.

If the version tag is precise, OTOH, (i.e., something other than
'dev'), then presumably the provider of the link can be trusted to
have identified what version it is.  IIUC, those source control sites
let you download tarballs of arbitrary versions, so one could in
principle issue download releases of exact source snapshots.  (Indeed,
it's not a bad way to go about it.)