Best practices for simultaneously installed versioned packages?

[Ned Deily]

In article <4B42B45E.9070900 at hastings.org>,
 Larry Hastings <larry at hastings.org> wrote:
> Ned Deily wrote:
> > Also, setuptools (and, its successor, distribute, which supports Python 
> > 3) allow the installation and management of multiple versions of a 
> > package within one python site-library instance.
> That sounds lovely too, but I can't figure out what facility setuptools 
> / distribute permits that.  Could you be more specific?  A link to the 
> documentation for this feature would be much appreciated.

By default, easy_install from setuptools/distribute uses version 
information from a package's setup.py to qualify the package name and 
manipulate python's sys.path to ensure the most recent version is the 
one found by default.  There are options to easy_install which control 
this.  See in particular the easy_install "--multi-version" command-line 
option (the links here are to those for the Distribute fork of 
setuptools):

http://packages.python.org/distribute/easy_install.html

If you need to declare specific version dependencies for other packages, 
you can do so in setup.py.  See the Declaring Dependencies section of 
the setuptools API documentation:

http://packages.python.org/distribute/setuptools.html

Much of the magic is handled by setuptools version of pkg_resources:

http://packages.python.org/distribute/pkg_resources.html

-- 
 Ned Deily,
 nad at acm.org