[Python-checkins] cpython: Issue #15544: Fix Decimal.__float__ to work with payload-carrying NaNs.
mark.dickinson
python-checkins at python.org
Fri Aug 24 19:53:25 CEST 2012
http://hg.python.org/cpython/rev/49014c59b31f
changeset: 78744:49014c59b31f
parent: 78742:150c58d98a5d
user: Mark Dickinson <mdickinson at enthought.com>
date: Fri Aug 24 18:53:10 2012 +0100
summary:
Issue #15544: Fix Decimal.__float__ to work with payload-carrying NaNs.
files:
Lib/decimal.py | 8 +++++++-
Lib/test/test_decimal.py | 16 ++++++++++++++++
Misc/NEWS | 2 ++
Modules/_decimal/_decimal.c | 18 +++++++++++++++++-
4 files changed, 42 insertions(+), 2 deletions(-)
diff --git a/Lib/decimal.py b/Lib/decimal.py
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -1601,7 +1601,13 @@
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
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -1942,6 +1942,22 @@
for d, n, r in test_triples:
self.assertEqual(str(round(Decimal(d), n)), r)
+ 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):
Decimal = self.decimal.Decimal
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -32,6 +32,8 @@
Library
-------
+- Issue #15544: Fix Decimal.__float__ to work with payload-carrying NaNs.
+
- Issue #15776: Allow pyvenv to work in existing directory with --clean.
- Issue #15249: BytesGenerator now correctly mangles From lines (when
diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -3357,7 +3357,23 @@
{
PyObject *f, *s;
- s = dec_str(dec);
+ if (mpd_isnan(MPD(dec))) {
+ if (mpd_issnan(MPD(dec))) {
+ PyErr_SetString(PyExc_ValueError,
+ "cannot convert signaling NaN to float");
+ return NULL;
+ }
+ if (mpd_isnegative(MPD(dec))) {
+ s = PyUnicode_FromString("-nan");
+ }
+ else {
+ s = PyUnicode_FromString("nan");
+ }
+ }
+ else {
+ s = dec_str(dec);
+ }
+
if (s == NULL) {
return NULL;
}
--
Repository URL: http://hg.python.org/cpython
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