How image installs work [was Re: The image question]

[Ryan Schmidt]

On Mar 10, 2007, at 10:11, Daniel J. Luke wrote:

> The image mode solution Jordan is proposing would let you upgrade  
> libiconv without breaking anything, but you really wouldn't be  
> upgrading libiconv (as everything you previously built against it  
> would still be using the old version).

Seems to me that it would be ideal if I could have version A of a  
library installed, then install a whole bunch of software that  
depends on that library. Then install a new version B of the library  
which breaks backward compatibility. Keep both versions of the  
library installed at the same time. Attempting to uninstall version A  
would show you which other packages still depend on version A of the  
library, so that you can rebuild those packages against version B.  
Once you've done all that, version A can be uninstalled.

Not sure what changes would need to be made in MacPorts to allow  
this, whether it's the image thing we're talking about here or  
something else. It would just be nice to be able to avoid a repeat of  
something like the Gettext Fiasco of 2006, where upgrading gettext  
destroyed most other installed software.