The real-life problem is something like
P = pp qq
T = pp/obj/p.o rr/obj/r.o
CFLAGS = -c
CFLAGS += $(if $(filter $(@D:/obj=),$(P)),-g)
all: $(T)
$(T):
@echo $@ $(CFLAGS)
$ make -f test-2.mk
pp/obj/p.o -c -g
rr/obj/r.o -c
Many thanks.
James
Paul D. Smith wrote:
> %% "James" <[EMAIL PROTECTED]> writes:
>
> j> Thanks. This seesm to work as well.
>
> j> CFLAGS = -c
> j> CFLAGS += $(shell [ $(foreach f,$(P),$(filter $(f),$@)) ] && echo -g)
>
> Well... yeah. But... ugh! :-|
>
> You're invoking that shell EVERY TIME you evaluate CFLAGS; and I mean
> _in addition to_ the shell that's actually doing the echo.
>
> If you're going to do this you might as well use make's builtin $(if
> ...) function instead of calling out to the shell:
>
> CFLAGS += $(if $(filter $@,$(P)),-g)
>
> Note that (a) you don't need the foreach even the way you wrote it
> originally because filter tests _each_ of its arguments against each of
> the possibilities; there can be more than one, and (b) if you swap them
> (since $@ is only one item) you'll get better performance.
>
>
> If it were me, I'd still probably use target-specific variables rather
> than something like the above. Seems cleaner to me.
>
> But, either of these is better than using $(shell ...), IMO.
>
> Cheers!
>
> --
> -------------------------------------------------------------------------------
> Paul D. Smith <[EMAIL PROTECTED]> Find some GNU make tips at:
> http://www.gnu.org http://make.paulandlesley.org
> "Please remain calm...I may be mad, but I am a professional." --Mad Scientist
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