[Distutils] Disabling --single-version-externally-managed

[Phillip J. Eby]

At 02:54 PM 9/1/2007 -0700, Toshio Kuratomi wrote:
>Toshio Kuratomi wrote:
> >
> > This code creates an unordered list because you might have already had
> > to place something after one of the duplicate locations that this code
> > is removing.  We need to do a sort of the entire list after each add +
> > duplicate removal run.
>
>Here's a quick and dirty patch.  It's correct but it's inefficient.  A
>better sort algorithm would help some.  Refactoring code so we call a
>sort method after we finish adding entries to the path would be even better.
>
>I'll test how this affects packaging tonight.

Please, please stop and back up a minute.   appreciate your eagerness 
to help, really, but right now I can't trust the correctness of the 
initial system against which you are performing your tests.  You've 
got crazy stuff on sys.path, you appear to be calling insert_on() 
(which isn't a documented API), and you're manually creating .pth 
files, among other things.

So before you do anything else, please restore your system to 
something which consists *only* of files generated by setuptools or 
easy_install without *any* added hacks, workarounds, or manually 
edited files.  That also means NO scripts that were not generated by 
easy_install.

If you *must* have other scripts, there is an undocumented internal 
feature that you can use to specify a script's requirements such that 
they override the default package versions.  What you have to do is 
add a __requires__ definition to the script, e.g.:

    __requires__= 'TurboGears>1.0', 'FibbledyDee<27.2'

This definition must be in the actual script run by Python.  When 
pkg_resources is initially imported, any __requires__ requirements 
are given higher precedence than the default versions.  You must, 
however, still import pkg_resources, and it must be imported *after* 
setting __requires__, not before.

Assuming I understand your requirements, you should be able to 
accomplish everything you want using only this one feature, plus 
single-version eggs for system default packages, and multi-version 
eggs (i.e. *no* .pth files) for everything else.

It should not be necessary for you to generate or edit any files, use 
other undocumented APIs, or anything else.