Determining what a port will install... (more than pretty-print-*)

[Eric Schuele]

Hello,

Is there a way to determine exactly what a particular port will install 
on my machine?

Doing a `make pretty-print-run-depends-list` will show me all of its 
requirements... but I am interested in the difference between its 
requirements and what I already have on my machine.  If I have 7 out of 
the 10 requirements.... I would like the remaining 3 listed for me.

Is there something in place which provides this?

-- 
Regards,
Eric