On 26 Sep 2002, Tom Hughes wrote:
> Andy Dougherty <[EMAIL PROTECTED]> wrote:
>
> > > The problem here is that the rule in the Makefile that causes it to
> > > rerun Configure.pl if any of the Configure.pl generated files is out
> > > of date clashes with the recently introduced edit to stop Configure.pl
> > > updating a file that hasn't actually changed.
> >
> > I think that the 'recently-introduced-edit' is wrong. Make's dependency
> > system requires that the stated commands actually bring something
> > up-to-date.
>
> On the other hand, without that edit it winds up rebuilding everything
> every time you run Configure, even if it doesn't have to...
Yes. That is correct expected 'make' behavior (assuming the dependencies
are correctly listed). By analogy, a Makefile can also assume that
cc -c foo.c
will re-run the compiler, not just run it only if the compiler decides the
output will change in some significant way.
Yes, I know that's often annoying. I often change things where I *know*
that not everything needs to be rebuilt. In those cases, I don't rely on
'make' to get it right. I manually get it right -- either by running a
shell script to rebuild just what needs to be rebuilt, or by judicious use
of 'touch' to pretend I rebuilt everything, or by use of cccache to speed
up rebuilds, or by some other trick.
These are, of course, obvious tricks, and I sometimes wish I didn't have
to do them. However, the alternative is to have incorrect dependencies in
the Makefile and rely on manually rebuilding everything that needs to be
rebuilt. I don't think that's a good plan.
--
Andy Dougherty [EMAIL PROTECTED]
