[Python-Dev] Status of packaging in 3.3

[Nick Coghlan]

On Thu, Jun 21, 2012 at 2:44 PM, Chris McDonough <chrism at plope.com> wrote:
> All of these are really pretty minor issues compared with the main benefit
> of not needing to ship everything with everything else. The killer feature
> is that developers can specify dependencies and users can have those
> dependencies installed automatically in a cross-platform way.  Everything
> else is complete noise if this use case is not served.

Cool. This is the kind of thing we need recorded in a PEP - there's a
lot of domain knowledge floating around in the heads of packaging
folks that needs to be captured so we can know *what the addition of
packaging to the standard library is intended to fix*.

And, like it or not, setuptools has a serious PR problem due to the
fact it monkeypatches the standard library, uses *.pth files to alter
sys.path for every installed application by default, actually *uses*
the ability to run code in *.pth files and has hard to follow
documentation to boot. I *don't* trust that I fully understand the
import system on any machine with setuptools installed, because it is
demonstrably happy to install state to the file system that will
affect *all* Python programs running on the machine.

A packaging PEP needs to explain:
- what needs to be done to eliminate any need for monkeypatching
- what's involved in making sure that *.pth are *not* needed by default
- making sure that executable code in implicitly loaded *.pth files
isn't used *at all*

I *think* trying to achieve this is actually the genesis of the
original distribute fork, that subsequently became distutils2 as Tarek
discovered how much of the complexity in setuptools was actually due
to the desire to *not* officially fork distutils (and instead
monkeypatch it, effectively creating a runtime fork).

However, for those of us that weren't directly involved, this is all
still a strange mystery dealt with by other people. I've cribbed
together bits and pieces just from following the fragments of the
discussions that have happened on python-dev and at PyCon US, but if
we want the madness to ever stop, then *the problems with the status
quo* need to be written down so that other core developers can
understand them.

In fact, I just remembered that Tarek *has* written a lot of this
down, just not in PEP form: http://www.aosabook.org/en/packaging.html

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia