Re: how to include dependencies only if includes changed

[Pete Johnson]

Mark,

See http://make.paulandlesley.org/autodep.html for a good way to handle
auto dependencies in make. Using the methods described in the article,
you will only build dependencies when they are needed.

-Pete

On 11/8/09, Mark Galeck (CW) <address@hidden> wrote:

Hello,

Suppose for each .c file such as foobar.c I have generated a makefile foobar.d file, that lists dependencies of foobar.o on files included in foobar.c.

There are many .d files and each of them has many dependencies, so if I just blindly do

-include $(OBJS:.o=.d)

then it takes a lot of time for make to just get started.  What I want, is to only include all of those *.d when needed, that is, when some include file has been modified.  I want this whenever a user calls

>make target

for any target.  How to do this?
--------------------------

What follows below is my solution to this problem, but it only works for
>make
(default target)
and can be extended to any fixed number of other targets, but not to general target such as
>make foobar.o
where foobar.c is any .c file


The solution,
simplified somewhat to show you just the gist of it,
is to generate another makefile called "included" like this:

chooseIncl:
        ($(MAKE) -q lastIncl && ( $(MAKE) noIncl & touch lastIncl)) || ($(MAKE) incl & touch lastIncl)

lastIncl:\
foobar.h\
foobar1.h\
(...)


(lastIncl depends on all the included files).
If you don't know DOS, the way the rule for chooseIncl works, is that if any included files have changed, then
$(MAKE) incl
is called, otherwise
$(MAKE) noIncl
is called


then include "included" at the top of the main makefile,
and put in the main makefile (where "all" is the original default target):

incl noIncl: all

ifeq (incl, $(MAKECMDGOALS))
-include $(ALL_OBJS:.o=.d)
endif





_______________________________________________
Help-make mailing list
address@hidden
http://lists.gnu.org/mailman/listinfo/help-make