Adding options framework variables that depend on variables coming after bsd.port.pre.mk

[Don Lewis]

On 23 Mar, Naram Qashat wrote:
> I'm wanting to add an options framework LIB_DEPENDS that depends on
> variables that normally come after bsd.port.pre.mk.
> 
> In this case, I am trying to add a UTEMPTER_LIB_DEPENDS on
> sysutils/libutempter, but I want to check OPSYS and OSVERSION beforehand,
> since base FreeBSD 9.x contains utempter while any earlier FreeBSDs as
> well as non-FreeBSD OSes don't contain it and need the port.
> 
> I cannot place the UTEMPTER_LIB_DEPENDS line after bsd.port.pre.mk because
> the options framework doesn't see it then, but I also cannot wrap it
> around an if conditional using OPSYS and OSVERSION before bsd.port.pre.mk
> because those variables aren't set yet.
> 
> I've been told that there is a workaround, but I was not told what the
> workaround was. Does anyone know how this can be acomplished?

Maybe something like:

UTEMPTER_LIB_DEPENDS=${FOO}

.include <bsd.port.pre.mk>

.if ${OPSYS} ... && ${OSVERSION} ...
FOO=	what you want to add to LIB_DEPENDS
.endif