Index: Lib/fractions.py =================================================================== --- Lib/fractions.py (revision 71808) +++ Lib/fractions.py (working copy) @@ -56,7 +56,7 @@ __slots__ = ('_numerator', '_denominator') # We're immutable, so use __new__ not __init__ - def __new__(cls, numerator=0, denominator=1): + def __new__(cls, numerator=0, denominator=None): """Constructs a Fraction. Takes a string like '3/2' or '1.5', another Fraction, or a @@ -65,8 +65,13 @@ """ self = super(Fraction, cls).__new__(cls) - if type(numerator) not in (int, long) and denominator == 1: - if isinstance(numerator, basestring): + if denominator is None: + if isinstance(numerator, Rational): + self._numerator = numerator.numerator + self._denominator = numerator.denominator + return self + + elif isinstance(numerator, basestring): # Handle construction from strings. m = _RATIONAL_FORMAT.match(numerator) if m is None: @@ -93,18 +98,22 @@ if m.group('sign') == '-': numerator = -numerator - elif isinstance(numerator, Rational): - # Handle copies from other rationals. Integrals get - # caught here too, but it doesn't matter because - # denominator is already 1. - other_rational = numerator - numerator = other_rational.numerator - denominator = other_rational.denominator + else: + raise TypeError("argument should be a string " + "or a Rational instance") + elif (isinstance(numerator, Rational) and + isinstance(denominator, Rational)): + numerator, denominator = ( + numerator.numerator * denominator.denominator, + denominator.numerator * numerator.denominator + ) + else: + raise TypeError("both arguments should be " + "Rational instances") + if denominator == 0: raise ZeroDivisionError('Fraction(%s, 0)' % numerator) - numerator = operator.index(numerator) - denominator = operator.index(denominator) g = gcd(numerator, denominator) self._numerator = numerator // g self._denominator = denominator // g Index: Lib/test/test_fractions.py =================================================================== --- Lib/test/test_fractions.py (revision 71808) +++ Lib/test/test_fractions.py (working copy) @@ -60,14 +60,20 @@ self.assertEquals((7, 15), _components(F(7, 15))) self.assertEquals((10**23, 1), _components(F(10**23))) + self.assertEquals((3, 77), _components(F(F(3, 7), 11))) + self.assertEquals((-9, 5), _components(F(2, F(-10, 9)))) + self.assertEquals((2486, 2485), _components(F(F(22, 7), F(355, 113)))) + self.assertRaisesMessage(ZeroDivisionError, "Fraction(12, 0)", F, 12, 0) self.assertRaises(TypeError, F, 1.5) self.assertRaises(TypeError, F, 1.5 + 3j) - self.assertRaises(TypeError, F, F(1, 2), 3) self.assertRaises(TypeError, F, "3/2", 3) + self.assertRaises(TypeError, F, 3, 0j) + self.assertRaises(TypeError, F, 3, 1j) + def testFromString(self): self.assertEquals((5, 1), _components(F("5"))) self.assertEquals((3, 2), _components(F("3/2")))