establish installed dependency not in portfile

[db]

On 8 Oct 2017, at 01:17, Ryan Schmidt <ryandesign at macports.org> wrote:
> py-numpy requires a Fortran compiler. Xcode doesn't contain one, so we must use one provided by MacPorts. You can choose which compiler to use by using variants:

> For modern systems, the default gcc port that the compilers portgroup uses used to be gcc6, and was changed to gcc7 a few days ago:
> https://github.com/macports/macports-ports/commit/c347ac662f932c0db8b15ec982eb4a563174bcfc

Since py27-numpy is the only port installed requiring gcc7, I rather choose gcc6 which is used by many others instead. Is there any way to install a port like scapy, which ultimately depends on py27-numpy built by default by gcc7, using gcc6 instead, i.e., to pass a variant to a dependency of the port to be installed? Or, is installing the dependency variant, then setting it to not requested, next installing the dependent port, the only way?