alternative options for ports

[Sebastian Schulze Struchtrup]

I would like to poll if there is any need for an extension to the 
current menu-driven config frontend.
My idea was to implement a kind of alternative options, like 
radio-buttons in a gui, using "dialog --menu" or something like this.
Not enable/disable options, but a way to select one option out of a few 
others.
For a new port (the lxr source code cross referencer) I will need a 
selection of one of three database clients to use and one of two 
indexing/search engine.
Please correct me if if there is yet a way to achieve this other than 
coding directly in the ports' makefile.

Will there be any use for some other ports (in the future?).
I would go to implement this in bsd.port.mk if this is favoured and 
would make sense for others.
Otherwise, I would implement a way in the ports makefile or using a 
command line/environment option like WITH_DB=xxxx.

I would be pleased to get some feedback.

Thanks,
Sebastian Schulze Struchtrup