Index: Lib/decimal.py =================================================================== --- Lib/decimal.py (revision 62685) +++ Lib/decimal.py (working copy) @@ -1649,9 +1649,6 @@ else: return -1 - def __round__(self): - return self._round_down(0) - def _round_up(self, prec): """Rounds away from 0.""" return -self._round_down(prec) @@ -1687,9 +1684,6 @@ else: return -self._round_down(prec) - def __ceil__(self): - return self._round_ceiling(0) - def _round_floor(self, prec): """Rounds down (not towards 0 if negative)""" if not self._sign: @@ -1697,9 +1691,6 @@ else: return -self._round_down(prec) - def __floor__(self): - return self._round_floor(0) - def _round_05up(self, prec): """Round down unless digit prec-1 is 0 or 5.""" if prec and self._int[prec-1] not in '05': @@ -1707,6 +1698,102 @@ else: return -self._round_down(prec) + def __round__(self, n=None): + """Round self to the nearest integer, or to a given precision. + + If only one argument is supplied, round a finite Decimal + instance self to the nearest integer. If self is infinite or + a NaN then a Python exception is raised. If self is finite + and lies exactly halfway between two integers then it is + rounded to the integer with even last digit. + + >>> round(Decimal('123.456')) + 123 + >>> round(Decimal('-456.789')) + -457 + >>> round(Decimal('-3.0')) + -3 + >>> round(Decimal('2.5')) + 2 + >>> round(Decimal('3.5')) + 4 + >>> round(Decimal('Inf')) + Traceback (most recent call last): + ... + ... + ... + OverflowError: cannot round an infinity + >>> round(Decimal('NaN')) + Traceback (most recent call last): + ... + ... + ... + ValueError: cannot round a NaN + + If a second argument n is supplied, self is rounded to n + decimal places using the rounding mode for the current + context. + + For an integer n, round(self, -n) is exactly equivalent to + self.quantize(Decimal('1En')). + + >>> round(Decimal('123.456'), 0) + Decimal('123') + >>> round(Decimal('123.456'), 2) + Decimal('123.46') + >>> round(Decimal('123.456'), -2) + Decimal('1E+2') + >>> round(Decimal('-Infinity'), 37) + Decimal('NaN') + >>> round(Decimal('sNaN123'), 0) + Decimal('NaN123') + + """ + if n is not None: + # two-argument form: use the equivalent quantize call + if not isinstance(n, int): + raise TypeError('Second argument to round should be an integer') + exp = _dec_from_triple(0, '1', -n) + return self.quantize(exp) + + # one-argument form + if self._is_special: + if self.is_nan(): + raise ValueError("cannot round a NaN") + else: + raise OverflowError("cannot round an infinity") + return int(self._rescale(0, ROUND_HALF_EVEN)) + + def __floor__(self): + """Return the floor of self, as an integer. + + For a finite Decimal instance self, return the greatest + integer n such that n <= self. If self is infinite or a NaN + then a Python exception is raised. + + """ + if self._is_special: + if self.is_nan(): + raise ValueError("cannot round a NaN") + else: + raise OverflowError("cannot round an infinity") + return int(self._rescale(0, ROUND_FLOOR)) + + def __ceil__(self): + """Return the ceiling of self, as an integer. + + For a finite Decimal instance self, return the least integer n + such that n >= self. If self is infinite or a NaN then a + Python exception is raised. + + """ + if self._is_special: + if self.is_nan(): + raise ValueError("cannot round a NaN") + else: + raise OverflowError("cannot round an infinity") + return int(self._rescale(0, ROUND_CEILING)) + def fma(self, other, third, context=None): """Fused multiply-add. Index: Lib/test/test_decimal.py =================================================================== --- Lib/test/test_decimal.py (revision 62685) +++ Lib/test/test_decimal.py (working copy) @@ -1158,6 +1158,94 @@ self.assertEqual(float(d1), 66) self.assertEqual(float(d2), 15.32) + #floor + test_pairs = [ + ('123.00', 123), + ('3.2', 3), + ('3.54', 3), + ('3.899', 3), + ('-2.3', -3), + ('-11.0', -11), + ('0.0', 0), + ('-0E3', 0), + ] + for d, i in test_pairs: + self.assertEqual(math.floor(Decimal(d)), i) + self.assertRaises(ValueError, math.floor, Decimal('-NaN')) + self.assertRaises(ValueError, math.floor, Decimal('sNaN')) + self.assertRaises(ValueError, math.floor, Decimal('NaN123')) + self.assertRaises(OverflowError, math.floor, Decimal('Inf')) + self.assertRaises(OverflowError, math.floor, Decimal('-Inf')) + + #ceiling + test_pairs = [ + ('123.00', 123), + ('3.2', 4), + ('3.54', 4), + ('3.899', 4), + ('-2.3', -2), + ('-11.0', -11), + ('0.0', 0), + ('-0E3', 0), + ] + for d, i in test_pairs: + self.assertEqual(math.ceil(Decimal(d)), i) + self.assertRaises(ValueError, math.ceil, Decimal('-NaN')) + self.assertRaises(ValueError, math.ceil, Decimal('sNaN')) + self.assertRaises(ValueError, math.ceil, Decimal('NaN123')) + self.assertRaises(OverflowError, math.ceil, Decimal('Inf')) + self.assertRaises(OverflowError, math.ceil, Decimal('-Inf')) + + #round, single argument + test_pairs = [ + ('123.00', 123), + ('3.2', 3), + ('3.54', 4), + ('3.899', 4), + ('-2.3', -2), + ('-11.0', -11), + ('0.0', 0), + ('-0E3', 0), + ('-3.5', -4), + ('-2.5', -2), + ('-1.5', -2), + ('-0.5', 0), + ('0.5', 0), + ('1.5', 2), + ('2.5', 2), + ('3.5', 4), + ] + for d, i in test_pairs: + self.assertEqual(round(Decimal(d)), i) + self.assertRaises(ValueError, round, Decimal('-NaN')) + self.assertRaises(ValueError, round, Decimal('sNaN')) + self.assertRaises(ValueError, round, Decimal('NaN123')) + self.assertRaises(OverflowError, round, Decimal('Inf')) + self.assertRaises(OverflowError, round, Decimal('-Inf')) + + #round, two arguments; this is essentially equivalent + #to quantize, which is already extensively tested + test_triples = [ + ('123.456', -4, '0E+4'), + ('123.456', -3, '0E+3'), + ('123.456', -2, '1E+2'), + ('123.456', -1, '1.2E+2'), + ('123.456', 0, '123'), + ('123.456', 1, '123.5'), + ('123.456', 2, '123.46'), + ('123.456', 3, '123.456'), + ('123.456', 4, '123.4560'), + ('123.455', 2, '123.46'), + ('123.445', 2, '123.44'), + ('Inf', 4, 'NaN'), + ('-Inf', -23, 'NaN'), + ('sNaN314', 3, 'NaN314'), + ] + for d, n, r in test_triples: + self.assertEqual(str(round(Decimal(d), n)), r) + + + def test_eval_round_trip(self): #with zero