diff --git a/Doc/library/decimal.rst b/Doc/library/decimal.rst index eda09e47fb8..7b858068552 100644 --- a/Doc/library/decimal.rst +++ b/Doc/library/decimal.rst @@ -281,9 +281,10 @@ Decimal objects Construct a new :class:`Decimal` object based from *value*. - *value* can be an integer, string, tuple, or another :class:`Decimal` object. If - no *value* is given, returns ``Decimal("0")``. If *value* is a string, it - should conform to the decimal numeric string syntax:: + *value* can be an integer, string, tuple, or another :class:`Decimal` + object. If no *value* is given, returns ``Decimal("0")``. If *value* is a + string, it should conform to the decimal numeric string syntax after leading + and trailing whitespace characters are removed:: sign ::= '+' | '-' digit ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' @@ -313,6 +314,10 @@ Decimal objects Once constructed, :class:`Decimal` objects are immutable. + .. versionchanged:: 2.6 + leading and trailing whitespace characters are permitted when + creating a Decimal instance from a string. + Decimal floating point objects share many properties with the other built-in numeric types such as :class:`float` and :class:`int`. All of the usual math operations and special methods apply. Likewise, decimal objects can be copied, @@ -973,6 +978,9 @@ method. For example, ``C.exp(x)`` is equivalent to >>> Decimal("3.4445") + Decimal(0) + Decimal("1.0023") Decimal("4.44") + This method implements the to-number operation of the IBM + specification. If the argument is a string, no leading or trailing + whitespace is permitted. .. method:: Context.Etiny() diff --git a/Lib/decimal.py b/Lib/decimal.py index 8b548216143..7e245161791 100644 --- a/Lib/decimal.py +++ b/Lib/decimal.py @@ -523,6 +523,8 @@ class Decimal(object): Decimal("314") >>> Decimal(Decimal(314)) # another decimal instance Decimal("314") + >>> Decimal(' 3.14 \\n') # leading and trailing whitespace okay + Decimal("3.14") """ # Note that the coefficient, self._int, is actually stored as @@ -538,7 +540,7 @@ class Decimal(object): # From a string # REs insist on real strings, so we can too. if isinstance(value, basestring): - m = _parser(value) + m = _parser(value.strip()) if m is None: if context is None: context = getcontext() @@ -3533,7 +3535,16 @@ class Context(object): return rounding def create_decimal(self, num='0'): - """Creates a new Decimal instance but using self as context.""" + """Creates a new Decimal instance but using self as context. + + This method implements the to-number operation of the + IBM Decimal specification.""" + + if isinstance(num, basestring) and num != num.strip(): + return self._raise_error(ConversionSyntax, + "no trailing or leading whitespace is " + "permitted.") + d = Decimal(num, context=self) if d._isnan() and len(d._int) > self.prec - self._clamp: return self._raise_error(ConversionSyntax, @@ -5148,7 +5159,7 @@ _parser = re.compile(r""" # A numeric string consists of: (?P\d*) # with (possibly empty) diagnostic information. ) # \s* - $ + \Z """, re.VERBOSE | re.IGNORECASE).match _all_zeros = re.compile('0*$').match diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py index 03cff604bb0..2135637e9d8 100644 --- a/Lib/test/test_decimal.py +++ b/Lib/test/test_decimal.py @@ -429,6 +429,10 @@ class DecimalExplicitConstructionTest(unittest.TestCase): #just not a number self.assertEqual(str(Decimal('ugly')), 'NaN') + #leading and trailing whitespace permitted + self.assertEqual(str(Decimal('1.3E4 \n')), '1.3E+4') + self.assertEqual(str(Decimal(' -7.89')), '-7.89') + def test_explicit_from_tuples(self): #zero @@ -517,6 +521,10 @@ class DecimalExplicitConstructionTest(unittest.TestCase): self.assertEqual(str(d), '456789') d = nc.create_decimal('456789') self.assertEqual(str(d), '4.57E+5') + # leading and trailing whitespace should result in a NaN; + # spaces are already checked in Cowlishaw's test-suite, so + # here we just check that a trailing newline results in a NaN + self.assertEqual(str(nc.create_decimal('3.14\n')), 'NaN') # from tuples d = Decimal( (1, (4, 3, 4, 9, 1, 3, 5, 3, 4), -25) ) diff --git a/Misc/NEWS b/Misc/NEWS index e625c3c9cde..51d27315ff6 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -351,6 +351,10 @@ Core and builtins Library ------- +- Issue #1780: The Decimal constructor now accepts arbitrary leading + and trailing whitespace when constructing from a string. + Context.create_decimal no longer accepts trailing newlines. + - Decimal.as_tuple(), difflib.find_longest_match() and inspect functions that returned a tuple now return a named tuple.