determining the how and why of a port dependencies

[René J.V. Bertin]

Hi,

I'm using Brad's VM to investigate co-installability of Qt 4 and 5 and KDE4 with the future KF5 ports. We started recreating the MacPorts a week or so ago, so I just had a look at the dependencies that would need to be installed for kde4-baseapps.

I was very surprised to see unexpected dependencies like port:gtk3 and port:llvm-35 appear in the (long) list. Is there a way to figure out what leads to these dependencies?

I realise this is related to the recent question about tools to display dependency graphs. At the time I didn't see anything but an academic use. Now I must say that if there isn't already a way to obtain the information, it'd be a great feature to add (GSoC??).
It doesn't have to be graphical (unless it's really interactive); something like `port whydepends foo  libbar`  and `port whyrdepends foo libbar` would probably be fine. Correction: those would be required in addition to anything graphical for those of us working remotely; a remote VNC desktop connection spanning half the globe (Cali - France) just isn't conductive to being productive ...

R.