At 02:13 PM 12/22/2005 +0000, Paul Moore wrote: >On 12/22/05, M.-A. Lemburg <[EMAIL PROTECTED]> wrote: > > Ian Bicking wrote: > > > I'm still finding it impossible to use multiple versions of a package > > > unless none of them show up in a .pth file (i.e., none are available > > > without requiring), I get a VersionConflict. > > > > This comes up every now and then when discussing the benefits > > of easy_install. > > > > I'd really like to understand what the use case is for having > > multiple versions of a package around. > > > > Note that sys.modules (the registry of loaded modules) does > > not support having multiple versions of a module loaded. > >I think the point is to allow multiple versions to be installed on the >system, but allow an individual program, at run time, to specify which >one is to be loaded. There will never be more than one version loaded >in any specific instance, but if program A requires version 1 of >package X, and program B requires version 2 of package X, both can run >without needing a reinstall of package X in between. > >Of course, this is also possible via PYTHONPATH manipulations, or >sys.path modifications in the program before doing the import. All >setuptools is doing is to provide a common infrastructure for handling >this.
Yes, Paul is correct; supporting multiple programs that use different versions of a module is indeed the primary use case. Also, during development and debugging it can be quite convenient to switch versions of a dependency back and forth to identify the source of a problem. _______________________________________________ Distutils-SIG maillist - [email protected] http://mail.python.org/mailman/listinfo/distutils-sig
