how to determine whether a port is a slave port?

[Oliver Eikemeier]

Mark Linimon wrote:

> One of the things that I would like to have available for the
> database in my ports monitoring code is an indication of whether
> or not a  port is a slave port.  The Porter's Handbook recommends
> that the MASTERDIR makevar be used to establish that, but does
> not make it clear whether its use is mandatory or not.  However,
> there are over 300 ports that do not seem to use this convention.
> Most seem to use the "${.CURDIR}/.." convention, although a few
> seem to use PORTSDIR directly.
> 
> So, without wanting to start a bikeshed, are these just remnants
> of a time before MASTERDIR was introduced?  Is there a consensus
> on how slave ports ought to be handled?

Since FreshPorts is having problems with that too, I suggest that
a port is a slave port if and only if MASTERDIR is set, and to let
us fix the other ports. That would make it easier for portlint too.

Concerning ${.CURDIR}/../.. vs. ${PORTSDIR} I'm undecided. Whats the
problem with having both?

-Oliver