Re: $(datadir) and @datadir@

[Ralf Wildenhues]

* Christian Parpart wrote on Tue, Feb 13, 2007 at 12:45:04PM CET:
> On Thursday 08 February 2007 20:47:53 Albert Chin wrote:
> >
> > If you use $(datadir), the user can override it at build time (e.g.
> > make datadir='<path>'). Not so with @datadir@ where the @datadir@
> > string is replaced in-place.
> 
> there's also a third way: ${datadir} which I can't understand the difference 
> of - is there?

As far as `make' is concerned, $(foo) and ${foo} are equivalent.

Sometimes it is useful however to use a notation that is understood by
all of: make, shell, perl (and others).  Then ${foo} has advantages.

Remember that AC_CONFIG_FILES() can list arbitrary files as output, from
an Autoconf POV all it does is substitute some @variables@ in FILE.in
with values.  (It's automake that looks for FILE.am for each such FILE
and then takes them as input to create FILE.in.)

Cheers,
Ralf