Can we have a -xxx_view none or null to unset the view? Could even be a viewer type that does nothing. I don't like the out-of-band -xxx_view_cancel.
Barry Smith <bsm...@petsc.dev> writes: > ALL the other options are sticky. Calling setFromOptions() twice does not > change the value of rtol etc etc etc that was set the last time and even > -ksp_monitor is sticky, why are the viewers so special in that they are the > only ones that are not sticky? Is not consistent, doesn't make sense, when > -ksp_monitor is sticky. It is just a freak feature of the implementation of > PetscOptionsGetViewer() that no one realized was there when they wrote it > (probably me :-)). > > > > > >> On Jan 22, 2023, at 1:16 PM, Jed Brown <j...@jedbrown.org> wrote: >> >> Matthew Knepley <knep...@gmail.com> writes: >> >>> On Sun, Jan 22, 2023 at 1:06 PM Barry Smith <bsm...@petsc.dev> wrote: >>> >>>> >>>> That makes incrementally adding new options to an existing object >>>> difficult, since each call to setFromOptions() screws up previous calls. >>>> >>>> We already have >>>> >>>> -ksp_monitor_cancel >>>> -ksp_converged_reason_view_cancel >>>> >>> >>> Let me address it another way. If I understand correctly, what happens >>> currently is that at each ViewFromOptions() call, the database is inspected >>> and if a *_view is found, then the view is executed. So when you replace >>> the database, if this option is not found then nothing happens. This seems >>> to satisfy a kind of options locality. If instead we make some options >>> sticky, like -ksp_view, so that once given they never expire, this would >>> make the code exceedingly hard to reason about, especially if options are >>> set deep inside something, before a user is knowingly doing things. This >>> does not sound like the right model to me. >> >> We could have something like PetscOptionsMerge() if one wants to preserve >> previously set options while adding some new ones (without tainting the >> global database). I don't like stickiness in general (a key reason why CMake >> is impossible to reason about and best practice is to run rm -rf * && cmake >> .. -DALL_THE_OPTIONS).
