Ian Bicking: the old part of his blog

Re: Site packages considered harmful comment 000

What major packaging system allows for multiple parallel installations of the same library? Not just in Python, in anything?

Gentoo's portage has SLOTs. AFAIK this is exactly it. I have many standard libs in multiple versions on my system.

With Portage different versions of a single package can coexist on a system. While other distributions tend to name their package to those versions (like freetype and freetype2) Portage uses a technology called SLOTs. An ebuild declares a certain SLOT for its version. Ebuilds with different SLOTs can coexist on the same system. For instance, the freetype package has ebuilds with SLOT="1" and SLOT="2" [1].
Comment on Site packages considered harmful comment 000
by Fabian