Hi,

I saw a feature in portage, the gentoo package manager, that I think could be interresting to have. They call it slots, and it is the ability they have to install multiple versions of the same package at the same time. There are many uses for that, for example to install multiple versions of the same kernel (to make shure you don't lose the materiel support with an upgrade), or even multiple versions of the same library.

Recently I was interrested in a package, openscenegraph, and there are two major versions that are very different. If a package need the version 1, the version 2 would not do. What are our possibilities now ? We can create two package, called openscenegraph and openscenegraph2. But then, do we have to do it on all the packages on the system ? How do we know when we upgrade a package if we should change its name or not ?

A better solution (from my point of view) would be to add a variable in pkgbuild that would tell if two versions of the package can be installed at the same time or not. It could take 3 values :
- 'no' : two versions mustn't be installed at the same time
- 'yes': two versions (or more) can be installed at the same time. There must not be file conflicts
- 'latest': two versions can be installed at the same time. If there is file conflicts, the file from the latest package is kept.

You could argue it is not simple enough for ArchLinux but I would answer that it is not very complicated (at least from the user point of view). Moreover, if we simplifies too much, we end up with a system that is too simple and can't handle some situations shat should be handled.

This is just an idea, and I might one day come with a patch. i hope it would be accepted then. Thanks.