Re: how to methodically generate a set of rules?

[mathieu lacage]

> again, i have a given list of C source files, each of which has the
> following structure:
>
>         blah.c:
>
>         #ifdef OBJ_fred
>         ... what will be compiled to generate fred.o ...
>         #endif
>
>         #ifdef OBJ_astro
>         ... what will be compiled to generate astro.o
>         #endif
>
>         ... and so on ...
>
>  there is no clear pattern between the name of the source file and
> the names of the object files that it can generate.  each source file
> will be compiled several times, defining a different preprocessor
> directive each time to generate the corresponding object file.  so
> far, so good?
>
>  for a file like the one above, the generated makefile rule would
> resemble:
>
> fred.o astro.o:  blah.c
>         ... funky rule to build each object file ...
>
>  now, given the list of source files, for each source file, i could
> easily generate the list of corresponding object files using "grep"
> so, for a given ${SRCFILE}, i would have:
>
>  OBJFILES := $(addsuffix .o,
>                 $(shell grep -h "^\#ifdef OBJ_" ${SRCFILE} | \
>                 sed -e "s/^\#ifdef OBJ_//"))
>  

let's define a make function:
gen-obj = $(addsuffix .o, $(shell grep -h "^\#ifdef OBJ_" $(1)} | sed -e 
"s/^\#ifdef OBJ_//"))
then, a small rule template:
define rule_template
$(call gen-obj $(1)): $(1)
    # ... funky rule ... #
endef
and then instantiate that template:
$(foreach src,$(SRC_FILES),$(eval rule_template,$(src))

hope this helps,
Mathieu