def _temporary_exponent_bounds(emin, emax):
old_emin = mpfr.mpfr_get_emin()
mpfr.mpfr_set_emin(emin)
try:
old_emax = mpfr.mpfr_get_emax()
mpfr.mpfr_set_emax(emax)
try:
yield
finally:
mpfr.mpfr_set_emax(old_emax)
finally:
mpfr.mpfr_set_emin(old_emin)
def test__temporary_exponent_bounds(self):
# Failed calls to _temporary_exponent_bounds shouldn't affect emin or
# emax.
original_emin = mpfr.mpfr_get_emin()
original_emax = mpfr.mpfr_get_emax()
# Call to _temporary_exponent_bounds should restore original values.
with _temporary_exponent_bounds(-10, 10):
self.assertEqual(mpfr.mpfr_get_emin(), -10)
self.assertEqual(mpfr.mpfr_get_emax(), 10)
self.assertEqual(mpfr.mpfr_get_emin(), original_emin)
self.assertEqual(mpfr.mpfr_get_emax(), original_emax)
# Even erroneous calls should restore originals.
with self.assertRaises(OverflowError):
with _temporary_exponent_bounds(-10, 10 ** 100):
pass
self.assertEqual(mpfr.mpfr_get_emin(), original_emin)
self.assertEqual(mpfr.mpfr_get_emax(), original_emax)
with self.assertRaises(OverflowError):
with _temporary_exponent_bounds(-10 ** 100, 10):
pass
self.assertEqual(mpfr.mpfr_get_emin(), original_emin)
self.assertEqual(mpfr.mpfr_get_emax(), original_emax)
with self.assertRaises(OverflowError):
with _temporary_exponent_bounds(-10 ** 100, 10 ** 100):
pass
self.assertEqual(mpfr.mpfr_get_emin(), original_emin)
self.assertEqual(mpfr.mpfr_get_emax(), original_emax)
