Re: How to test if a variable is something or empty?

[Sam Ravnborg]

On Fri, Oct 24, 2008 at 07:00:41PM -0500, Peng Yu wrote:
> On Fri, Oct 24, 2008 at 4:37 PM, Philip Guenther <address@hidden> wrote:
> > On Fri, Oct 24, 2008 at 1:59 PM, Peng Yu <address@hidden> wrote:
> >> I have the following code. I'm wondering how to put them together into
> >> one if statement?
> >>
> >> ifeq ($(MAKECMDGOALS), all)
> >> -include .dep
> >> endif
> >>
> >> ifeq ($(MAKECMDGOALS), )
> >> -include .dep
> >> endif
> >
> > Don't you _really_ want to test whether they are doing a "make clean"?  If 
> > so:
> >
> > # don't include .dep if they're doing a make clean
> > ifeq ($(filter clean,$(MAKECMDGOALS)),)
> >  -include .dep
> > endif
> >
> > If there are other fake targets that should disable .dep inclusion,
> > just include them in the first argument to $(filter)
> 
> No. I'm not asking how to make clean. I just want to know how to
> combine the two if statements. The commands inside each if statements
> can be anything, but they are the same.
> 
> ifeq ($(MAKECMDGOALS), all)
> some command
> endif
> 
> ifeq ($(MAKECMDGOALS), )
> same as above command
> endif

Like this:

ifeq ($(filter all, $(MAKECMDGOALS)),)
#bla
endif

You just filter out the "all" target so the result is
empty if all was specified.

But as Philip said consider what you try to do. Do the right
thing happen when you do "make foo" also where foo is some random
target?

        Sam