substitution vs expansion in Makefile.am

[John Calcote]

hi list,

Newbie question here: Is it better to do this in a Makefile.am:

   install-exec-hook:
           $(mkdir_p) $(DESTDIR)@syslogdir@

or this:

   install-exec-hook:
          $(mkdir_p) $(DESTDIR)$(syslogdir)

assuming, of course, that I called AC_SUBST(syslogdir) in configure.ac?

The first will expand to $(prefix)/..., so you'd have the option of
changing the resulting directory by passing prefix= on the make
command line. The second will allow you to change the resulting
directory with either prefix= or syslogdir= on the make command line.
I guess you'd get a bit more flexibility by using the second option
because you could change the syslogdir without changing the prefix.
But, is there a conventional, or more correct approach?

If you have an opinion on it, then what's your rationale?

Thanks in advance,
John