expose PETScOptions.clear() in the Python interface

[Nico Schlömer]

In https://github.com/FEniCS/dolfin/blob/master/dolfin/la/PETScOptions.h, there are two functions by the name clear: One with a string argument to clear a specific option, one without to clear all options.

I suppose it's the fact that those two bear the same name that makes it impossible to expose both in Python.

The request for clearing all options has come up twice recently (once by myself, once by dajuno, so I suppose it's worthwhile fixing it.

Perhaps clear_all is an appropriate name.

[Jan Blechta]

It seems that that both clearing a single option and all the options is supported

from dolfin import *
from petsc4py import PETSc

PETScOptions.set("foo")
PETScOptions.set("bar")
assert 'foo' in PETSc.Options().getAll()
assert 'bar' in PETSc.Options().getAll()

PETScOptions.clear('foo')
assert 'bar' in PETSc.Options().getAll()

PETScOptions.clear()
assert len(PETSc.Options().getAll()) == 0

Can you provide a MWE?

[Nico Schlömer]

The line

PETScOptions.clear()

gives

TypeError: clear() takes exactly 1 argument (0 given)

for me on 2016.2. Certainly that's something that's been fixed in the meantime.

[Jan Blechta]

Yes, resolved by 0cd6e916.