migration handling

[Jeremy Lavergne]

> Yeah, a temp table sounds good.
> 
> What about the reinstall MacPorts part? I could have sworn that
> 'selfupdate' was good enough; that the installers were system
> OS-dependent, but running 'selfupdate' got you to an OS-apathetic
> installation. But, the migration instructions state reinstalling is
> necessary. Is that still the case? If so, the migration phase would
> need to write out the table and then instruct the user to reinstall.
> It culd then pick up from that temp table on first run. Or as part of
> the installer, though rebuilding a bunch of ports would be lengthy for
> an installer.

Well, MacPorts now tracks the OS version for each installed port. So at best it would work as you suggest: everything would get upgraded/reinstalled. Unfortunately, sometimes the dependencies are missing and can gum up the works.

Now that we're adding build-time conflicts, we might also be able to address opportunistic linking at build time (an old package is still active while rebuilding another). Until that's hammered out though (it's not even released yet) we need to have people uninstall everything prior to reinstalling.