Re: how to create a single rule to build a directory as necessary

[Sam Steingold]

Paul Smith wrote:
> On Tue, 2009-09-22 at 13:19 -0400, Sam Steingold wrote:
> > Do I need to explicitly type
> >
> > gllib/foo gllib/bar : config.status
> >         mkdir -p gllib; cd gllib; make
>
> You still have to consider prerequisites.  Is it true that the one and
> only reason gllib/foo or gllib/bar might need to be rebuilt is because
> of a change to config.status?

OK, you got me.

what I _actually_ really need is this:
if config.status is newer, gllib should be removed and rebuilt from scratch.
otherwise the usual PHONY/cd+make is good enough.

so,
I have this:
---------------------------------------------------
.PHONY : gllib

gllib:
        mkdir -p $@
        if test ! -f $@/Makefile; then sh config.status $@/Makefile depfiles; fi
        cd $@ && $(MAKE) CFLAGS="$(SUBDIR_CFLAGS)"
---------------------------------------------------
alas, when config.status has been changed, gllib must be removed before make 
will do its job properly.

so, what should I do?

one thing that just occurred to me - maybe I should modify the config.status 
rule to read:

config.status : configure
        $(RM) config.cache
 >new>    rm -rf gllib
        sh config.status --recheck

does this look right?