establish installed dependency not in portfile

[Rainer Müller]

On 2017-10-08 12:17, db wrote:
> 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?

Selected variants will be passed down to dependencies, if they are not
yet installed, even if the port given on the command line does not have
such a variant.

In your case, assuming py27-numpy is not yet installed, the command
  sudo port install scapy +gcc6
would install py27-numpy +gcc6 as dependency.

Rainer