Re: how to deal if source code and object file are in different directory?

[Philip Guenther]

On 8/30/06, Lin George <address@hidden> wrote:
> Suppose I define two macros,
>
> OBJ_DIR = debug/foo.o debug/goo.o
> SRC_DIR = src/foo.c src/goo.c
>
> how should I write a rule to compile foo.c and goo.c
> into foo.o and goo.o and put them into debug
> sub-directory?

Well, here's a pattern rule to compile _any_ .c file under 'src' into
a .o under 'debug'

debug/%.o: src/%.c
       $(COMPILE.c) -o $@ $<

If you wanted that to _only_ apply to the files listed in OBJ_DIR, you
would change that to a static pattern rule (check the GNU make info
pages for details):

$(OBJ_DIR): debug/%.o: src/%.c
       $(COMPILE.c) -o $@ $<


BTW, it's kinda odd to name a variable containing filenames with the
suffix "_DIR".  In practically every makefile I've ever seen or
written, a variable named SRC_DIR would contain just the directory of
the source files.  The list of source files would be named SRCS or
similar.


Philip Guenther