subport and keyword questions/suggestions

[René J.V. Bertin]

On Sunday February 15 2015 19:58:14 Mojca Miklavec wrote:
Hi Mojca,

> Example: perl5.16 and perl5.20 could be treated as "alternative_to"
> and many applications that need Perl just as a runtime dependency
> could happily use either one or the other. But for many ports it
> *does* matter which one is installed. 

I think the answer about what I have in mind is simply an equivalent to letting ports require a specific variant of a dependency. 
> 
> If your KDE app depends on qt5-mac[-devel]-kde (if qt5-mac is not
> sufficient), then specifying something like "qt5-mac-kde
> alternative_to qt5-mac" won't help you in any way. It would just mean
> that users would be allowed to uninstall qt5-mac-kde, replace it with
> qt5-mac ... and then your KDE app would happily stop working.

No. If qt5-mac-kde provides (an alternative to) qt5-mac that doesn't mean that qt5-mac is an alternative to qt5-mac-kde. It just means that users can install qt5-mac-kde, and any application that declares a dependency on qt5-mac will see that dependency fulfilled (without doing a path: style dependency check).
OTOH, it should be possible for 2 ports to declare themselves mutual alternatives, for instance between qt5-mac and qt5-mac-devel, but one could also envision such a relationship between Xorg and XFree.

R.