foo-snapshot / foo-diff convenience functions

[Ryan Schmidt]

> On Oct 19, 2016, at 4:50 AM, René J.V. Bertin <rjvbertin at gmail.com> wrote:
> 
> It's not that uncommon that one includes a PortGroup that adds build settings (e.g. to depends_lib) in a port where those settings are irrelevant and even unwanted.

No, that situation should not be common, nor indeed present at all.


> For instance, a port providing translation files for a KDE port would probably need to include a KDE PortGroup but doesn't need to depend on Qt.

I haven't looked at the kde portgroup specifically. Maybe the portgroup needs additional options to handle different types of ports (e.g. libraries vs. translation files), or maybe there need to be separate portgroup.