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

[Jay Sachs]

On Mar 12, 2007, at 4:47 PM, Ryan Schmidt wrote:

> 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.
>

It seems that image mode doesn't preclude this. One could imagine  
operations like

   port upgrade-depending-ports <dependency-name>[@version]

which upgrades all packages depending on dependency-name to the  
latest (or specified even) version,

   port delete-unused-inactive-images [name ...]

which removes the images of all unreferenced inactive packages.

Note I'm saying "imagine" operations. Not being a macports developer,  
I can't comment on the feasibility of implementing those operations.

jay