Fix type interaction with other Rational classes.

See python/cpython#119236

Author: scoder

Diff for: CHANGES.rst

@@ -12,6 +12,9 @@ ChangeLog
 * Using ``complex`` numbers in division shows better tracebacks.
   https://github.com/python/cpython/pull/102842
 
+* Mixed calculations with other ``Rational`` classes could return the wrong type.
+  https://github.com/python/cpython/issues/119189
+
 
 1.18 (2024-04-03)
 -----------------

Diff for: src/quicktions.pyx

@@ -1487,7 +1487,7 @@ cdef forward(a, b, math_func monomorphic_operator, pyoperator, handle_complex=Tr
         return monomorphic_operator(an, ad, (<Fraction>b)._numerator, (<Fraction>b)._denominator)
     elif isinstance(b, int):
         return monomorphic_operator(an, ad, b, 1)
-    elif isinstance(b, (Fraction, Rational)):
+    elif isinstance(b, Fraction):
         return monomorphic_operator(an, ad, b.numerator, b.denominator)
     elif isinstance(b, float):
         return pyoperator(_as_float(an, ad), b)

Diff for: src/test_fractions.py

@@ -135,7 +135,7 @@ def __float__(self):
         assert False, "__float__ should not be invoked"
 
 
-class DummyFraction(fractions.Fraction):
+class DummyFraction(quicktions.Fraction):
     """Dummy Fraction subclass for copy and deepcopy testing."""
 
 
@@ -200,6 +200,197 @@ def test_quicktions_limits(self):
 def _components(r):
     return (r.numerator, r.denominator)
 
+def typed_approx_eq(a, b):
+    return type(a) == type(b) and (a == b or math.isclose(a, b))
+
+class Symbolic:
+    """Simple non-numeric class for testing mixed arithmetic.
+    It is not Integral, Rational, Real or Complex, and cannot be conveted
+    to int, float or complex. but it supports some arithmetic operations.
+    """
+    def __init__(self, value):
+        self.value = value
+    def __mul__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(f'{self} * {other}')
+    def __rmul__(self, other):
+        return self.__class__(f'{other} * {self}')
+    def __truediv__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(f'{self} / {other}')
+    def __rtruediv__(self, other):
+        return self.__class__(f'{other} / {self}')
+    def __mod__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(f'{self} % {other}')
+    def __rmod__(self, other):
+        return self.__class__(f'{other} % {self}')
+    def __pow__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(f'{self} ** {other}')
+    def __rpow__(self, other):
+        return self.__class__(f'{other} ** {self}')
+    def __eq__(self, other):
+        if other.__class__ != self.__class__:
+            return NotImplemented
+        return self.value == other.value
+    def __str__(self):
+        return f'{self.value}'
+    def __repr__(self):
+        return f'{self.__class__.__name__}({self.value!r})'
+
+class SymbolicReal(Symbolic):
+    pass
+numbers.Real.register(SymbolicReal)
+
+class SymbolicComplex(Symbolic):
+    pass
+numbers.Complex.register(SymbolicComplex)
+
+class Rat:
+    """Simple Rational class for testing mixed arithmetic."""
+    def __init__(self, n, d):
+        self.numerator = n
+        self.denominator = d
+    def __mul__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.numerator * other.numerator,
+                              self.denominator * other.denominator)
+    def __rmul__(self, other):
+        return self.__class__(other.numerator * self.numerator,
+                              other.denominator * self.denominator)
+    def __truediv__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.numerator * other.denominator,
+                              self.denominator * other.numerator)
+    def __rtruediv__(self, other):
+        return self.__class__(other.numerator * self.denominator,
+                              other.denominator * self.numerator)
+    def __mod__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        d = self.denominator * other.numerator
+        return self.__class__(self.numerator * other.denominator % d, d)
+    def __rmod__(self, other):
+        d = other.denominator * self.numerator
+        return self.__class__(other.numerator * self.denominator % d, d)
+
+        return self.__class__(other.numerator / self.numerator,
+                              other.denominator / self.denominator)
+    def __pow__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.numerator ** other,
+                              self.denominator ** other)
+    def __float__(self):
+        return self.numerator / self.denominator
+    def __eq__(self, other):
+        if self.__class__ != other.__class__:
+            return NotImplemented
+        return (typed_approx_eq(self.numerator, other.numerator) and
+                typed_approx_eq(self.denominator, other.denominator))
+    def __repr__(self):
+        return f'{self.__class__.__name__}({self.numerator!r}, {self.denominator!r})'
+numbers.Rational.register(Rat)
+
+class Root:
+    """Simple Real class for testing mixed arithmetic."""
+    def __init__(self, v, n=F(2)):
+        self.base = v
+        self.degree = n
+    def __mul__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.base * other**self.degree, self.degree)
+    def __rmul__(self, other):
+        return self.__class__(other**self.degree * self.base, self.degree)
+    def __truediv__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.base / other**self.degree, self.degree)
+    def __rtruediv__(self, other):
+        return self.__class__(other**self.degree / self.base, self.degree)
+    def __pow__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.base, self.degree / other)
+    def __float__(self):
+        return float(self.base) ** (1 / float(self.degree))
+    def __eq__(self, other):
+        if self.__class__ != other.__class__:
+            return NotImplemented
+        return typed_approx_eq(self.base, other.base) and typed_approx_eq(self.degree, other.degree)
+    def __repr__(self):
+        return f'{self.__class__.__name__}({self.base!r}, {self.degree!r})'
+numbers.Real.register(Root)
+
+class Polar:
+    """Simple Complex class for testing mixed arithmetic."""
+    def __init__(self, r, phi):
+        self.r = r
+        self.phi = phi
+    def __mul__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.r * other, self.phi)
+    def __rmul__(self, other):
+        return self.__class__(other * self.r, self.phi)
+    def __truediv__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.r / other, self.phi)
+    def __rtruediv__(self, other):
+        return self.__class__(other / self.r, -self.phi)
+    def __pow__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.r ** other, self.phi * other)
+    def __eq__(self, other):
+        if self.__class__ != other.__class__:
+            return NotImplemented
+        return typed_approx_eq(self.r, other.r) and typed_approx_eq(self.phi, other.phi)
+    def __repr__(self):
+        return f'{self.__class__.__name__}({self.r!r}, {self.phi!r})'
+numbers.Complex.register(Polar)
+
+class Rect:
+    """Other simple Complex class for testing mixed arithmetic."""
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+    def __mul__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.x * other, self.y * other)
+    def __rmul__(self, other):
+        return self.__class__(other * self.x, other * self.y)
+    def __truediv__(self, other):
+        if isinstance(other, F):
+            return NotImplemented
+        return self.__class__(self.x / other, self.y / other)
+    def __rtruediv__(self, other):
+        r = self.x * self.x + self.y * self.y
+        return self.__class__(other * (self.x / r), other * (self.y / r))
+    def __rpow__(self, other):
+        return Polar(other ** self.x, math.log(other) * self.y)
+    def __complex__(self):
+        return complex(self.x, self.y)
+    def __eq__(self, other):
+        if self.__class__ != other.__class__:
+            return NotImplemented
+        return typed_approx_eq(self.x, other.x) and typed_approx_eq(self.y, other.y)
+    def __repr__(self):
+        return f'{self.__class__.__name__}({self.x!r}, {self.y!r})'
+numbers.Complex.register(Rect)
+
+class RectComplex(Rect, complex):
+    pass
 
 class FractionTest(unittest.TestCase):
 
@@ -795,20 +986,66 @@ def testMixedArithmetic(self):
         self.assertTypedEquals(0.9, 1.0 - F(1, 10))
         self.assertTypedEquals(0.9 + 0j, (1.0 + 0j) - F(1, 10))
 
+    def testMixedMultiplication(self):
         self.assertTypedEquals(F(1, 10), F(1, 10) * 1)
         self.assertTypedEquals(0.1, F(1, 10) * 1.0)
         self.assertTypedEquals(0.1 + 0j, F(1, 10) * (1.0 + 0j))
         self.assertTypedEquals(F(1, 10), 1 * F(1, 10))
         self.assertTypedEquals(0.1, 1.0 * F(1, 10))
         self.assertTypedEquals(0.1 + 0j, (1.0 + 0j) * F(1, 10))
 
+        self.assertTypedEquals(F(3, 2) * DummyFraction(5, 3), F(5, 2))
+        self.assertTypedEquals(DummyFraction(5, 3) * F(3, 2), F(5, 2))
+        self.assertTypedEquals(F(3, 2) * Rat(5, 3), Rat(15, 6))
+        self.assertTypedEquals(Rat(5, 3) * F(3, 2), F(5, 2))
+
+        self.assertTypedEquals(F(3, 2) * Root(4), Root(F(9, 1)))
+        self.assertTypedEquals(Root(4) * F(3, 2), 3.0)
+        self.assertEqual(F(3, 2) * SymbolicReal('X'), SymbolicReal('3/2 * X'))
+        self.assertRaises(TypeError, operator.mul, SymbolicReal('X'), F(3, 2))
+
+        self.assertTypedEquals(F(3, 2) * Polar(4, 2), Polar(F(6, 1), 2))
+        self.assertTypedEquals(F(3, 2) * Polar(4.0, 2), Polar(6.0, 2))
+        self.assertTypedEquals(F(3, 2) * Rect(4, 3), Rect(F(6, 1), F(9, 2)))
+        self.assertTypedEquals(F(3, 2) * RectComplex(4, 3), RectComplex(6.0+0j, 4.5+0j))
+        self.assertRaises(TypeError, operator.mul, Polar(4, 2), F(3, 2))
+        self.assertTypedEquals(Rect(4, 3) * F(3, 2), 6.0 + 4.5j)
+        self.assertEqual(F(3, 2) * SymbolicComplex('X'), SymbolicComplex('3/2 * X'))
+        self.assertRaises(TypeError, operator.mul, SymbolicComplex('X'), F(3, 2))
+
+        self.assertEqual(F(3, 2) * Symbolic('X'), Symbolic('3/2 * X'))
+        self.assertRaises(TypeError, operator.mul, Symbolic('X'), F(3, 2))
+
+    def testMixedDivision(self):
         self.assertTypedEquals(F(1, 10), F(1, 10) / 1)
         self.assertTypedEquals(0.1, F(1, 10) / 1.0)
         self.assertTypedEquals(0.1 + 0j, F(1, 10) / (1.0 + 0j))
         self.assertTypedEquals(F(10, 1), 1 / F(1, 10))
         self.assertTypedEquals(10.0, 1.0 / F(1, 10))
         self.assertTypedEquals(10.0 + 0j, (1.0 + 0j) / F(1, 10))
 
+        self.assertTypedEquals(F(3, 2) / DummyFraction(3, 5), F(5, 2))
+        self.assertTypedEquals(DummyFraction(5, 3) / F(2, 3), F(5, 2))
+        self.assertTypedEquals(F(3, 2) / Rat(3, 5), Rat(15, 6))
+        self.assertTypedEquals(Rat(5, 3) / F(2, 3), F(5, 2))
+
+        self.assertTypedEquals(F(2, 3) / Root(4), Root(F(1, 9)))
+        self.assertTypedEquals(Root(4) / F(2, 3), 3.0)
+        self.assertEqual(F(3, 2) / SymbolicReal('X'), SymbolicReal('3/2 / X'))
+        self.assertRaises(TypeError, operator.truediv, SymbolicReal('X'), F(3, 2))
+
+        self.assertTypedEquals(F(3, 2) / Polar(4, 2), Polar(F(3, 8), -2))
+        self.assertTypedEquals(F(3, 2) / Polar(4.0, 2), Polar(0.375, -2))
+        self.assertTypedEquals(F(3, 2) / Rect(4, 3), Rect(0.24, 0.18))
+        self.assertRaises(TypeError, operator.truediv, Polar(4, 2), F(2, 3))
+        self.assertTypedEquals(Rect(4, 3) / F(2, 3), 6.0 + 4.5j)
+        self.assertEqual(F(3, 2) / SymbolicComplex('X'), SymbolicComplex('3/2 / X'))
+        self.assertRaises(TypeError, operator.truediv, SymbolicComplex('X'), F(3, 2))
+
+        self.assertEqual(F(3, 2) / Symbolic('X'), Symbolic('3/2 / X'))
+        self.assertRaises(TypeError, operator.truediv, Symbolic('X'), F(2, 3))
+
+    def testMixedIntegerDivision(self):
         self.assertTypedEquals(0, F(1, 10) // 1)
         self.assertTypedEquals(0.0, F(1, 10) // 1.0)
         self.assertTypedEquals(10, 1 // F(1, 10))
@@ -835,6 +1072,26 @@ def testMixedArithmetic(self):
             self.assertTypedTupleEquals(divmod(-0.1, float('inf')), divmod(F(-1, 10), float('inf')))
             self.assertTypedTupleEquals(divmod(-0.1, float('-inf')), divmod(F(-1, 10), float('-inf')))
 
+        self.assertTypedEquals(F(3, 2) % DummyFraction(3, 5), F(3, 10))
+        self.assertTypedEquals(DummyFraction(5, 3) % F(2, 3), F(1, 3))
+        self.assertTypedEquals(F(3, 2) % Rat(3, 5), Rat(3, 6))
+        self.assertTypedEquals(Rat(5, 3) % F(2, 3), F(1, 3))
+
+        self.assertRaises(TypeError, operator.mod, F(2, 3), Root(4))
+        self.assertTypedEquals(Root(4) % F(3, 2), 0.5)
+        self.assertEqual(F(3, 2) % SymbolicReal('X'), SymbolicReal('3/2 % X'))
+        self.assertRaises(TypeError, operator.mod, SymbolicReal('X'), F(3, 2))
+
+        self.assertRaises(TypeError, operator.mod, F(3, 2), Polar(4, 2))
+        self.assertRaises(TypeError, operator.mod, F(3, 2), RectComplex(4, 3))
+        self.assertRaises(TypeError, operator.mod, Rect(4, 3), F(2, 3))
+        self.assertEqual(F(3, 2) % SymbolicComplex('X'), SymbolicComplex('3/2 % X'))
+        self.assertRaises(TypeError, operator.mod, SymbolicComplex('X'), F(3, 2))
+
+        self.assertEqual(F(3, 2) % Symbolic('X'), Symbolic('3/2 % X'))
+        self.assertRaises(TypeError, operator.mod, Symbolic('X'), F(2, 3))
+
+    def testMixedPower(self):
         # ** has more interesting conversion rules.
         self.assertTypedEquals(F(100, 1), F(1, 10) ** -2)
         self.assertTypedEquals(F(100, 1), F(10, 1) ** 2)
@@ -855,6 +1112,40 @@ def testMixedArithmetic(self):
         self.assertRaises(ZeroDivisionError, operator.pow,
                           F(0, 1), -2)
 
+        self.assertTypedEquals(F(3, 2) ** Rat(3, 1), F(27, 8))
+        self.assertTypedEquals(F(3, 2) ** Rat(-3, 1), F(8, 27))
+        self.assertTypedEquals(F(-3, 2) ** Rat(-3, 1), F(-8, 27))
+        self.assertTypedEquals(F(9, 4) ** Rat(3, 2), 3.375)
+        self.assertIsInstance(F(4, 9) ** Rat(-3, 2), float)
+        self.assertAlmostEqual(F(4, 9) ** Rat(-3, 2), 3.375)
+        self.assertAlmostEqual(F(-4, 9) ** Rat(-3, 2), 3.375j)
+        self.assertTypedEquals(Rat(9, 4) ** F(3, 2), 3.375)
+        self.assertTypedEquals(Rat(3, 2) ** F(3, 1), Rat(27, 8))
+        self.assertTypedEquals(Rat(3, 2) ** F(-3, 1), F(8, 27))
+        self.assertIsInstance(Rat(4, 9) ** F(-3, 2), float)
+        self.assertAlmostEqual(Rat(4, 9) ** F(-3, 2), 3.375)
+
+        self.assertTypedEquals(Root(4) ** F(2, 3), Root(4, 3.0))
+        self.assertTypedEquals(Root(4) ** F(2, 1), Root(4, F(1)))
+        self.assertTypedEquals(Root(4) ** F(-2, 1), Root(4, -F(1)))
+        self.assertTypedEquals(Root(4) ** F(-2, 3), Root(4, -3.0))
+        self.assertEqual(F(3, 2) ** SymbolicReal('X'), SymbolicReal('1.5 ** X'))
+        self.assertEqual(SymbolicReal('X') ** F(3, 2), SymbolicReal('X ** 1.5'))
+
+        self.assertTypedEquals(F(3, 2) ** Rect(2, 0), Polar(2.25, 0.0))
+        self.assertTypedEquals(F(1, 1) ** Rect(2, 3), Polar(1.0, 0.0))
+        self.assertTypedEquals(F(3, 2) ** RectComplex(2, 0), Polar(2.25, 0.0))
+        self.assertTypedEquals(F(1, 1) ** RectComplex(2, 3), Polar(1.0, 0.0))
+        self.assertTypedEquals(Polar(4, 2) ** F(3, 2), Polar(8.0, 3.0))
+        self.assertTypedEquals(Polar(4, 2) ** F(3, 1), Polar(64, 6))
+        self.assertTypedEquals(Polar(4, 2) ** F(-3, 1), Polar(0.015625, -6))
+        self.assertTypedEquals(Polar(4, 2) ** F(-3, 2), Polar(0.125, -3.0))
+        self.assertEqual(F(3, 2) ** SymbolicComplex('X'), SymbolicComplex('1.5 ** X'))
+        self.assertEqual(SymbolicComplex('X') ** F(3, 2), SymbolicComplex('X ** 1.5'))
+
+        self.assertEqual(F(3, 2) ** Symbolic('X'), Symbolic('1.5 ** X'))
+        self.assertEqual(Symbolic('X') ** F(3, 2), Symbolic('X ** 1.5'))
+
     def testMixingWithDecimal(self):
         # Decimal refuses mixed arithmetic (but not mixed comparisons)
         self.assertRaises(TypeError, operator.add,
@@ -1087,7 +1378,7 @@ def numerator(self):
             def denominator(self):
                 return type(self)(1)
 
-        f = fractions.Fraction(myint(1 * 3), myint(2 * 3))
+        f = F(myint(1 * 3), myint(2 * 3))
         self.assertEqual(f.numerator, 1)
         self.assertEqual(f.denominator, 2)
         self.assertEqual(type(f.numerator), myint)