handle variant dependency

[Bradley Giesbrecht]

The py25-gtk, py26-gtk, py27-gtk depend on cairo +x11.

Does MacPorts have a standard way of dealing with this?

I recall that the suggestion to test for a variant specific file and error if it is [not] present. In this case is there anything that could/would prevent a user from upgrading the variant away with --enforce-variants?


Regards,
Bradley Giesbrecht (pixilla)