make port to install to a different PREFIX

[Fernan Aguero]

Hi!

I'm the maintainer of the biology/emboss port. The port
installs by default to $PREFIX which, in most cases should
be $LOCALBASE (i.e. /usr/local).

EMBOSS is a big package, with lots of executable files. It
is thus not surprising that some of the executables have the
same name as those installed by other ports.

Right now these are the recorded conflicts:
CONFLICTS=      nss-* qmail-ldap2-* digest-*

To work around this, I was thinking about installing
biology/emboss by default to PREFIX/emboss.
However, I'm having problems in getting this to work.

This does not work:
CONFIGURE_ARGS+= --prefix=${PREFIX}/emboss

and neither does this:
PREFIX?= ${PREFIX}/emboss

because obviously 'Variable PREFIX is recursive.'

So, my problem is that I want to honour PREFIX but instead
of installing into PREFIX, I want to install into
PREFIX/emboss. Any ideas or suggestions about how to achieve
this? Or examples of ports already doing this?

The examples I've looked at are the ones in bsd.port.mk for
USE_X_PREFIX or USE_LINUX_PREFIX, but there is no recursion
here since in each case the PREFIX is independent of the
previous PREFIX (/usr/X11R6 and /compat/linux,
respectively).

Thanks in advance,

fernan