Canonical method of rebuilding makefiles?

[Miller, Bryan]

Hello all,

I have read and re-read section 3.5 "How Makefiles are Remade" in the GNU
make manual but I am still wrestling with correctly rebuilding a makefile to
include updated dependency files.  When I turn on -d I can see the makefile
being regenerated and the include files being read but I am not able to see
the updated variables.

#-----------------------------------------------
.PHONY: all

-include base_deps.mk
-include app_deps.mk

all: base_deps.mk
        @echo $(app_deps)

# regenerate the dependency files...
base_deps.mk:
        cqperl get_depends.pl
#-----------------------------------------------

The *_deps.mk files are generated by get_depends.pl.  Since they need to be
generated everytime I have added one of them as a dependency to the default
target.  If both files exist I get an echo of the string app_deps which is
defined in app_deps.mk.  If the files don't exist "cqperl get_depends.pl"
gets run and generates the files but the echo statement echos an empty
string ("").

Is there a better way to do this (double colon rule?)?  I have read section
3.5 (How Makefiles are Remade) of the GNU Make book (3.77) but it really
muddies the waters quite a bit.  It suggests that make will consider all
makefiles (and include.mk files) as targets and will rebuild them if a rule
is provide.  I have not found that to be true in clearmake GNU compat mode.
(NOTE: I have taken the makefile rule out in the above example.)

Cheers,
Bryan