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bpo-29534: _decimal difference with _pydecimal #65

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Merged
merged 1 commit into from
Feb 14, 2017
Merged

bpo-29534: _decimal difference with _pydecimal #65

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27 changes: 16 additions & 11 deletions Lib/_pydecimal.py
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Original file line number Diff line number Diff line change
Expand Up @@ -734,18 +734,23 @@ def from_float(cls, f):

"""
if isinstance(f, int): # handle integer inputs
return cls(f)
if not isinstance(f, float):
raise TypeError("argument must be int or float.")
if _math.isinf(f) or _math.isnan(f):
return cls(repr(f))
if _math.copysign(1.0, f) == 1.0:
sign = 0
sign = 0 if f >= 0 else 1
k = 0
coeff = str(abs(f))
elif isinstance(f, float):
if _math.isinf(f) or _math.isnan(f):
return cls(repr(f))
if _math.copysign(1.0, f) == 1.0:
sign = 0
else:
sign = 1
n, d = abs(f).as_integer_ratio()
k = d.bit_length() - 1
coeff = str(n*5**k)
else:
sign = 1
n, d = abs(f).as_integer_ratio()
k = d.bit_length() - 1
result = _dec_from_triple(sign, str(n*5**k), -k)
raise TypeError("argument must be int or float.")

result = _dec_from_triple(sign, coeff, -k)
if cls is Decimal:
return result
else:
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10 changes: 10 additions & 0 deletions Lib/test/test_decimal.py
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Expand Up @@ -1185,6 +1185,16 @@ def test_wide_char_separator_decimal_point(self):
self.assertEqual(format(Decimal('100000000.123'), 'n'),
'100\u066c000\u066c000\u066b123')

def test_decimal_from_float_argument_type(self):
class A(self.decimal.Decimal):
def __init__(self, a):
self.a_type = type(a)
a = A.from_float(42.5)
self.assertEqual(self.decimal.Decimal, a.a_type)

a = A.from_float(42)
self.assertEqual(self.decimal.Decimal, a.a_type)

class CFormatTest(FormatTest):
decimal = C
class PyFormatTest(FormatTest):
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2 changes: 2 additions & 0 deletions Misc/NEWS
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Expand Up @@ -10,6 +10,8 @@ What's New in Python 3.7.0 alpha 1?
Core and Builtins
-----------------

- bpo-29534: Fixed different behaviour of Decimal.from_float() for _decimal and _pydecimal.

- bpo-29438: Fixed use-after-free problem in key sharing dict.

- Issue #29319: Prevent RunMainFromImporter overwriting sys.path[0].
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