Re: makefile improvements

[Ben Pfaff]

John Darrington <address@hidden> writes:

> On Mon, Oct 12, 2009 at 08:56:08AM -0700, Ben Pfaff wrote:
>
>      >   $(POFILES): $(POTFILE)
>      >        $(MSGMERGE) $(top_srcdir)/$@ $(top_srcdir)/$(POTFILE) -o $@
>      >
>      > $(POTFILE) is a generated file, so it will be in $(top_builddir) not 
>      > $(top_srcdir).
>      
>      I hadn't realize that.
>      
>      When we make a distribution with "make dist", $(POTFILE) will be
>      distributed and thus it will be in the source directory.  Does
>      this mean that we have to cope with both possible locations?
>
> Is that something we can change?  Do we really need pspp.pot to be in
> the tarball?  If not, then I guess we will indeed have to cope with
> both locations.  And that is of course why the VPATH feature and the
> $< variable was invented.

I think I've found a satisfactory solution that avoids the need
to search for the path by hand.  POSIX requires $? to work even
though it does not require $< to work.  Since there is only one
target in this case, $? is always equivalent to $<.

The autoconf manual actually mentions this.  I had forgotten that
it had a chapter on VPATH:

       A simple workaround, and good practice anyway, is to use `$?' and
    `$@' when possible:

         VPATH = ../pkg/src
         f.c: if.c
                 cp $? $@

    but this does not generalize well to commands with multiple
    prerequisites.

We still do need to distribute pspp.pot, but this is easier to
read than searching by hand.
-- 
Ben Pfaff 
http://benpfaff.org