Doing more with curses.buildlink3.mk

["Johnny C. Lam" <jlam%pkgsrc.org@localhost>]

Please review the attached patch to curses.buildlink3.mk.  The goal of 
the patch is to allow a user to choose to use ncurses over whatever 
curses is installed in the base system.  This can be done by setting the 
following in /etc/mk.conf:

        CURSES_DEFAULT= ncurses

curses.buildlink3.mk should be included by packages that need *some* 
curses implementation instead of a particular one.

        Thanks,

        -- Johnny C. Lam

Index: curses.buildlink3.mk
===================================================================
RCS file: /cvsroot/pkgsrc/mk/curses.buildlink3.mk,v
retrieving revision 1.5
diff -u -r1.5 curses.buildlink3.mk
--- curses.buildlink3.mk        3 Nov 2007 15:17:42 -0000       1.5
+++ curses.buildlink3.mk        22 Feb 2008 16:42:04 -0000
@@ -1,24 +1,86 @@
 # $NetBSD: curses.buildlink3.mk,v 1.5 2007/11/03 15:17:42 rillig Exp $
 #
-# This file should be included by Makefiles for packages that use curses.
-# It checks whether a native curses implementation is available, or
-# otherwise adds a dependency on ncurses.
+# This Makefile fragment is meant to be included by packages that require
+# any curses implementation instead of one particular one.  The available
+# curses implementations are "curses" if built-in, and "ncurses".
 #
 # If a package genuinely requires ncurses, then it should directly include
 # ncurses/buildlink3.mk instead of this file in the package Makefile and
 # additionally set USE_NCURSES=yes.
 #
+# === User-settable variables ===
+#
+# CURSES_DEFAULT
+#      This value represents the type of curses we wish to use on the
+#      system.  Setting this to "curses" means that the system curses
+#      implementation is fine.  Setting this to "ncurses" means that
+#      we want to use ncurses instead of the system curses.
+#
+#      Possible: curses, ncurses
+#      Default: (depends)
+#
+# === Variables set by this file ===
+#
+# CURSES_TYPE
+#      The name of the selected curses implementation.
+
+CURSES_BUILDLINK3_MK:= ${CURSES_BUILDLINK3_MK}+
 
+.include "bsd.fast.prefs.mk"
+
+.if !empty(CURSES_BUILDLINK3_MK:M+)
+
+# _CURSES_PKGS is an exhaustive list of all of the curses implementations
+# that may be used with curses.buildlink3.mk.
+#
+_CURSES_PKGS?=         curses ncurses # ncursesw
+
+# Set the value of CURSES_DEFAULT depending on the platform and what's
+# available in the base system.
+#
+# - Interix has an unusual ncurses installation that is missing some
+#   shared libraries, but the ncurses/builtin.mk will take care of things
+#   for us.
+#
+.if ${OPSYS} == "Interix"
+CURSES_DEFAULT?=       ncurses
+.endif
+#
+# - If there is no curses implementation in the base system, then
+#   use ncurses instead.
+#
 .if !exists(/usr/include/curses.h) && \
     !exists(/usr/include/ncurses.h)
-.  include "../../devel/ncurses/buildlink3.mk"
+CURSES_DEFAULT?=       ncurses
 .else
+CURSES_DEFAULT?=       curses          # just use the system curses
+.endif
+
+_CURSES_ACCEPTED=      # empty
+.if exists(/usr/include/curses.h) || exists(/usr/include/ncurses.h)
+_CURSES_ACCEPTED+=     curses          # system curses exists
+.endif
+_CURSES_ACCEPTED+=     ncurses         # pkgsrc ncurses
+#_CURSES_ACCEPTED+=    ncursesw        # pkgsrc ncursesw
 
-# XXX this is ugly, but needed to get the BUILDLINK_TRANSFORM from builtin.mk;
-# on Interix, libncurses is static yet libcurses (also ncurses) is shared
-.  include "bsd.fast.prefs.mk"
-.  if ${OPSYS} == "Interix"
-.    include "../../devel/ncurses/buildlink3.mk"
+_CURSES_TYPE=          ${CURSES_DEFAULT}
+.  if !empty(_CURSES_ACCEPTED:M${_CURSES_TYPE})
+CURSES_TYPE=           ${_CURSES_TYPE}
+.  else
+CURSES_TYPE=           none
 .  endif
 
+.endif # CURSES_BUILDLINK3_MK
+
+.if ${CURSES_TYPE} == "none"
+PKG_FAIL_REASON=       \
+       "${_CURSES_TYPE} is not an acceptable curses type for ${PKGNAME}."
+.elif ${CURSES_TYPE} == "curses"
+#  Nothing to include here because we're using the system curses.
+.elif ${CURSES_TYPE} == "ncurses"
+USE_NCURSES=           yes
+.  include "../../devel/ncurses/buildlink3.mk"
+#.elif ${CURSES_TYPE} == "ncursesw"
+#USE_NCURSES=          yes
+#.  include "../../devel/ncursesw/buildlink3.mk"
 .endif