diff options
| -rw-r--r-- | Lib/decimal.py | 8 | ||||
| -rw-r--r-- | Lib/test/test_decimal.py | 16 | ||||
| -rw-r--r-- | Misc/NEWS | 2 |
3 files changed, 25 insertions, 1 deletions
diff --git a/Lib/decimal.py b/Lib/decimal.py index f5277c5..49de535 100644 --- a/Lib/decimal.py +++ b/Lib/decimal.py @@ -1555,7 +1555,13 @@ class Decimal(object): def __float__(self): """Float representation.""" - return float(str(self)) + if self._isnan(): + if self.is_snan(): + raise ValueError("Cannot convert signaling NaN to float") + s = "-nan" if self._sign else "nan" + else: + s = str(self) + return float(s) def __int__(self): """Converts self to an int, truncating if necessary.""" diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py index e46cd91..3ff855f 100644 --- a/Lib/test/test_decimal.py +++ b/Lib/test/test_decimal.py @@ -1518,6 +1518,22 @@ class DecimalUsabilityTest(unittest.TestCase): + def test_nan_to_float(self): + # Test conversions of decimal NANs to float. + # See http://bugs.python.org/issue15544 + Decimal = self.decimal.Decimal + for s in ('nan', 'nan1234', '-nan', '-nan2468'): + f = float(Decimal(s)) + self.assertTrue(math.isnan(f)) + sign = math.copysign(1.0, f) + self.assertEqual(sign, -1.0 if s.startswith('-') else 1.0) + + def test_snan_to_float(self): + Decimal = self.decimal.Decimal + for s in ('snan', '-snan', 'snan1357', '-snan1234'): + d = Decimal(s) + self.assertRaises(ValueError, float, d) + def test_eval_round_trip(self): #with zero @@ -109,6 +109,8 @@ Core and Builtins Library ------- +- Issue #15544: Fix Decimal.__float__ to work with payload-carrying NaNs. + - Issue #15249: BytesGenerator now correctly mangles From lines (when requested) even if the body contains undecodable bytes. |