Example of a port that relies on another port's sources

[Mike Edenfield]

Matthew Seaman wrote:
> Dear ports list,
> 
> I seem to remember a while back a discussion in the Porter's Handbook about
> having port X depend on the sources from port Y for building, and triggering
> automatic extraction of those sources.  However I can't see any mention of
> such a thing in the currently available version of the Porter's Handbook.
> 
> Can anyone point me towards an example of such a thing?  This is for a local
> company-internal piece of porting, not anything that will go into the FreeBSD
> ports tree, so I'm not too concerned if it's against policy nowadays.

I believe tk depends on the appropriate version of tcl source being present.