make install a port, but with a package?

[freebsd-questions at auscert.org.au]

Hi,

I have a bad feeling that this has been asked already, and not that long
ago, but I can't find it in my mailbox. Is there a variable I can set so
that running 'make install' in a port directory will cause it to download
the package, if available, and install that instead of building from
source?  In other words, the equivalent of 'portupgrade -NPP'. I have
looked at the .mk files and nothing in there seems to do that.

This is for the situation where portupgrade isn't installed yet, and I'd
like to install it quickly from packages so I don't have to wait for Ruby
to build. Sure, I could do it with pkg_add or sysinstall but it would be
neat to be able to do everything from the ports tree.

thanks,
joel