port dependents

[David Evans]

Jeremy Lavergne wrote:
> Well, there it is in the PortIndex.  dependencies.
>
And on top of this, if this command uses PortIndex information to 
calculate dependencies, why does it only do it for
ports that are installed since PortIndex contains dependency information 
for all ports.  This makes me think that registry information
is involved as well (or instead).  But then why doesn't it change 
immediately when I upgrade/install/uninstall a port?