[Python-Dev] PEP 365 (Adding the pkg_resources module)

[Phillip J. Eby]

At 12:59 PM 3/17/2008 -0500, Guido van Rossum wrote:
>On Mon, Mar 17, 2008 at 12:45 PM, Phillip J. Eby 
><pje at telecommunity.com> wrote:
> > At 12:17 PM 3/17/2008 -0500, Guido van Rossum wrote:
> >  >There will be no egg support in the standard library.
> >
> >  Are there any qualifications on that statement, or is this in the
> >  same category as "from __future__ import braces"?
>
>IIUC eggs are a method of package management that includes support for
>dependencies, multiple versions, and C extensions in zip files, as
>well as conventions for naming these and for encoding metadata (e.g.
>how to find out the version or the dependencies). This whole set of
>conventions is IMO too much to include into the stdlib ATM -- if only
>because it has proved controversial in the past. Maybe a few years
>from now it will be no longer controversial and then my objections
>will disappear.

So, does this mean that the bootstrap tool must not use eggs?  That 
seems a little bit odd, in that setuptools will at least need its 
.egg-info directory to get installed, and all of the people who'll be 
using this initially will be using it precisely in order to have 
support for eggs...

So, it might be simpler all around to just clear up the 
"controversy".  To the best of my recollection, only MAL and MvL have 
ever objected on Python-Dev to the idea of supporting eggs.

Note: I'm specifically segregating "egg support" from the topic of 
including setuptools or easy_install in the stdlib directly.  There 
are many legitimate reservations and open questions about the latter, 
including availability of volunteer support, choice of defaults, 
whether to replace distutils with setuptools, etc. etc.  I recognize 
and respect the validity of those issues, which is precisely why I 
withdrew setuptools from inclusion in Python 2.5.

However, regarding support for eggs, my understanding is that there 
were only two objections to eggs -- even at the time of the 2.5 
setuptools discussions.  And even though MvL objects to the idea of 
eggs in *principle*, I didn't read his recent posts as objecting to 
having the bootstrap tool download and install eggs in 
*practice*.  (Although I hope he will clarify that stance one way or 
the other.)

That leaves MAL, whose objections to PEP 365 centered on the API (he 
said he was "+1 on the concepts being added to the stdlib, -1 on 
adding the module in its current state").  Among other concerns, he 
wanted pkg_resources to be split into pkgutil and a new "egglib" 
module.  I don't have a problem with this in principle, if there were 
a pkg_resources module that reconstituted the merged API.  (But there 
are some practical problems with that approach, such as trying to 
split namespace package support between two theoretically-unrelated modules.)

I would guess, however, that MAL's issues with the pkg_resources API 
would not apply to a bootstrap module whose sole purpose was to 
download eggs and put them on sys.path.  Or, perhaps he would object 
*more*, I don't know.  We could certainly ask him, though.  :)

So, was there anyone else you were counting towards 
"controversy"?  The only other person I recall objecting to 
setuptools in any way on Python-Dev was effbot, and IIUC his 
objections were practical/administrative re: supporting easy_install 
and setuptools, not to the idea of .egg support in general.

In summary, I think the controversy on Python-Dev regarding .egg 
support has actually been over for some time now.