optionally include file within a Makefile

[Tim Kientzle]

Dan Langille wrote:
> On 18 Dec 2003 at 19:02, Dan Langille wrote:
>>My goal is provide a way to override values in a Makefile with values
>>from a local config file.
> 
> I'm getting further.  What's the proper way to do an include?

The best reference I've found for advanced make
usage is the FreeBSD source tree.  Here's an
excerpt from /usr/src/lib/libc/Makefile:

#
# If there is a machine dependent makefile, use it:
#
.if exists(${.CURDIR}/${MACHINE_ARCH}/Makefile.inc)
.include "${.CURDIR}/${MACHINE_ARCH}/Makefile.inc"
.endif