[petsc-dev] [Suggestion] Configure QOL Improvements

[Matthew Knepley]

On Wed, Oct 23, 2019 at 4:45 PM Jed Brown <jed at jedbrown.org> wrote:

> Matthew Knepley <knepley at gmail.com> writes:
>
> > On Wed, Oct 23, 2019 at 2:27 PM Jed Brown <jed at jedbrown.org> wrote:
> >
> >> Matthew Knepley via petsc-dev <petsc-dev at mcs.anl.gov> writes:
> >>
> >> > On Wed, Oct 23, 2019 at 11:24 AM Faibussowitsch, Jacob via petsc-dev <
> >> > petsc-dev at mcs.anl.gov> wrote:
> >> >> As I am largely unfamiliar with the internals of the configure
> process,
> >> >> this is potentially more of an involved change than I am imagining,
> >> given
> >> >> that many libraries likely have many small dependencies and hooks
> which
> >> >> have to be set throughout the configuration process, and so its
> possible
> >> >> not everything could be skipped.
> >> >>
> >> >
> >> > We had this many years ago. It was removed because the benefits did
> not
> >> > outweigh the costs.
> >>
> >> I don't know if it's still the case, but it should be possible to run
> >> non-interactively (like apt-get -y).  My bigger complaint is that
> >> missing dependencies aren't resolved in the first couple seconds.
> >>
> >
> > How do you know that you actually have something until you actually
> > run the tests? This is the classic misconception of pkg-config, "I'll
> > just believe the user", which generated 99% of user mail over the
> > first 20 years of PETSc.
>
> All other build systems get this right.  You're asking to build X and Y,
> where Y depends on Z, and there is no --download-Z or --with-Z.  You
> shouldn't need to build X before noticing that Z is unavailable.
>

That is an unreliable check for Z. You would not eliminate the case where
you give --with-Z, but the check fails, so Z is not available, but you do
not
find out until checking X or Y.

   Matt

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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