8000 bpo-32968: Make modulo and floor division involving Fraction and floa… · python/cpython@393f1ff · GitHub
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bpo-32968: Make modulo and floor division involving Fraction and float consistent with other operations (#5956)
Make mixed-type `%` and `//` operations involving `Fraction` and `float` objects behave like all other mixed-type arithmetic operations: first the `Fraction` object is converted to a `float`, then the `float` operation is performed as normal. This fixes some surprising corner cases, like `Fraction('1/3') % inf` giving a NaN. Thanks Elias Zamaria for the patch.
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4 files changed

+13
-12
lines changed

4 files changed

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-12
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‎Lib/fractions.py

Lines changed: 4 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -427,23 +427,18 @@ def _div(a, b):
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__truediv__, __rtruediv__ = _operator_fallbacks(_div, operator.truediv)
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def __floordiv__(a, b):
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def _floordiv(a, b):
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"""a // b"""
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return math.floor(a / b)
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434-
def __rfloordiv__(b, a):
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"""a // b"""
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return math.floor(a / b)
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__floordiv__, __rfloordiv__ = _operator_fallbacks(_floordiv, operator.floordiv)
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def __mod__(a, b):
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def _mod(a, b):
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"""a % b"""
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div = a // b
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return a - b * div
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def __rmod__(b, a):
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"""a % b"""
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div = a // b
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return a - b * div
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__mod__, __rmod__ = _operator_fallbacks(_mod, operator.mod)
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def __pow__(a, b):
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"""a ** b

‎Lib/test/test_fractions.py

Lines changed: 7 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -401,15 +401,19 @@ def testMixedArithmetic(self):
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self.assertTypedEquals(10.0 + 0j, (1.0 + 0j) / F(1, 10))
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self.assertTypedEquals(0, F(1, 10) // 1)
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self.assertTypedEquals(0, F(1, 10) // 1.0)
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self.assertTypedEquals(0.0, F(1, 10) // 1.0)
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self.assertTypedEquals(10, 1 // F(1, 10))
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self.assertTypedEquals(10**23, 10**22 // F(1, 10))
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self.assertTypedEquals(10, 1.0 // F(1, 10))
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self.assertTypedEquals(1.0 // 0.1, 1.0 // F(1, 10))
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self.assertTypedEquals(F(1, 10), F(1, 10) % 1)
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self.assertTypedEquals(0.1, F(1, 10) % 1.0)
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self.assertTypedEquals(F(0, 1), 1 % F(1, 10))
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self.assertTypedEquals(0.0, 1.0 % F(1, 10))
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self.assertTypedEquals(1.0 % 0.1, 1.0 % F(1, 10))
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self.assertTypedEquals(0.1, F(1, 10) % float('inf'))
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self.assertTypedEquals(float('-inf'), F(1, 10) % float('-inf'))
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self.assertTypedEquals(float('inf'), F(-1, 10) % float('inf'))
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self.assertTypedEquals(-0.1, F(-1, 10) % float('-inf'))
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# No need for divmod since we don't override it.
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‎Misc/ACKS

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Original file line numberDiff line numberDiff line change
@@ -1814,6 +1814,7 @@ Masazumi Yoshikawa
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Arnaud Ysmal
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Bernard Yue
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Moshe Zadka
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Elias Zamaria
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Milan Zamazal
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Artur Zaprzala
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Mike Zarnstorff

‎Misc/NEWS.d/next/Library/2018-03-18-15-57-32.bpo-32968.E4G7BO.rst

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1 @@
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Modulo and floor division involving Fraction and float should return float.

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