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- """Tests for binary operators on subtypes of built-in types."""
- import unittest
- from operator import eq, le, ne
- from abc import ABCMeta
- def gcd(a, b):
- """Greatest common divisor using Euclid's algorithm."""
- while a:
- a, b = b%a, a
- return b
- def isint(x):
- """Test whether an object is an instance of int."""
- return isinstance(x, int)
- def isnum(x):
- """Test whether an object is an instance of a built-in numeric type."""
- for T in int, float, complex:
- if isinstance(x, T):
- return 1
- return 0
- def isRat(x):
- """Test whether an object is an instance of the Rat class."""
- return isinstance(x, Rat)
- class Rat(object):
- """Rational number implemented as a normalized pair of ints."""
- __slots__ = ['_Rat__num', '_Rat__den']
- def __init__(self, num=0, den=1):
- """Constructor: Rat([num[, den]]).
- The arguments must be ints, and default to (0, 1)."""
- if not isint(num):
- raise TypeError("Rat numerator must be int (%r)" % num)
- if not isint(den):
- raise TypeError("Rat denominator must be int (%r)" % den)
- # But the zero is always on
- if den == 0:
- raise ZeroDivisionError("zero denominator")
- g = gcd(den, num)
- self.__num = int(num//g)
- self.__den = int(den//g)
- def _get_num(self):
- """Accessor function for read-only 'num' attribute of Rat."""
- return self.__num
- num = property(_get_num, None)
- def _get_den(self):
- """Accessor function for read-only 'den' attribute of Rat."""
- return self.__den
- den = property(_get_den, None)
- def __repr__(self):
- """Convert a Rat to a string resembling a Rat constructor call."""
- return "Rat(%d, %d)" % (self.__num, self.__den)
- def __str__(self):
- """Convert a Rat to a string resembling a decimal numeric value."""
- return str(float(self))
- def __float__(self):
- """Convert a Rat to a float."""
- return self.__num*1.0/self.__den
- def __int__(self):
- """Convert a Rat to an int; self.den must be 1."""
- if self.__den == 1:
- try:
- return int(self.__num)
- except OverflowError:
- raise OverflowError("%s too large to convert to int" %
- repr(self))
- raise ValueError("can't convert %s to int" % repr(self))
- def __add__(self, other):
- """Add two Rats, or a Rat and a number."""
- if isint(other):
- other = Rat(other)
- if isRat(other):
- return Rat(self.__num*other.__den + other.__num*self.__den,
- self.__den*other.__den)
- if isnum(other):
- return float(self) + other
- return NotImplemented
- __radd__ = __add__
- def __sub__(self, other):
- """Subtract two Rats, or a Rat and a number."""
- if isint(other):
- other = Rat(other)
- if isRat(other):
- return Rat(self.__num*other.__den - other.__num*self.__den,
- self.__den*other.__den)
- if isnum(other):
- return float(self) - other
- return NotImplemented
- def __rsub__(self, other):
- """Subtract two Rats, or a Rat and a number (reversed args)."""
- if isint(other):
- other = Rat(other)
- if isRat(other):
- return Rat(other.__num*self.__den - self.__num*other.__den,
- self.__den*other.__den)
- if isnum(other):
- return other - float(self)
- return NotImplemented
- def __mul__(self, other):
- """Multiply two Rats, or a Rat and a number."""
- if isRat(other):
- return Rat(self.__num*other.__num, self.__den*other.__den)
- if isint(other):
- return Rat(self.__num*other, self.__den)
- if isnum(other):
- return float(self)*other
- return NotImplemented
- __rmul__ = __mul__
- def __truediv__(self, other):
- """Divide two Rats, or a Rat and a number."""
- if isRat(other):
- return Rat(self.__num*other.__den, self.__den*other.__num)
- if isint(other):
- return Rat(self.__num, self.__den*other)
- if isnum(other):
- return float(self) / other
- return NotImplemented
- def __rtruediv__(self, other):
- """Divide two Rats, or a Rat and a number (reversed args)."""
- if isRat(other):
- return Rat(other.__num*self.__den, other.__den*self.__num)
- if isint(other):
- return Rat(other*self.__den, self.__num)
- if isnum(other):
- return other / float(self)
- return NotImplemented
- def __floordiv__(self, other):
- """Divide two Rats, returning the floored result."""
- if isint(other):
- other = Rat(other)
- elif not isRat(other):
- return NotImplemented
- x = self/other
- return x.__num // x.__den
- def __rfloordiv__(self, other):
- """Divide two Rats, returning the floored result (reversed args)."""
- x = other/self
- return x.__num // x.__den
- def __divmod__(self, other):
- """Divide two Rats, returning quotient and remainder."""
- if isint(other):
- other = Rat(other)
- elif not isRat(other):
- return NotImplemented
- x = self//other
- return (x, self - other * x)
- def __rdivmod__(self, other):
- """Divide two Rats, returning quotient and remainder (reversed args)."""
- if isint(other):
- other = Rat(other)
- elif not isRat(other):
- return NotImplemented
- return divmod(other, self)
- def __mod__(self, other):
- """Take one Rat modulo another."""
- return divmod(self, other)[1]
- def __rmod__(self, other):
- """Take one Rat modulo another (reversed args)."""
- return divmod(other, self)[1]
- def __eq__(self, other):
- """Compare two Rats for equality."""
- if isint(other):
- return self.__den == 1 and self.__num == other
- if isRat(other):
- return self.__num == other.__num and self.__den == other.__den
- if isnum(other):
- return float(self) == other
- return NotImplemented
- class RatTestCase(unittest.TestCase):
- """Unit tests for Rat class and its support utilities."""
- def test_gcd(self):
- self.assertEqual(gcd(10, 12), 2)
- self.assertEqual(gcd(10, 15), 5)
- self.assertEqual(gcd(10, 11), 1)
- self.assertEqual(gcd(100, 15), 5)
- self.assertEqual(gcd(-10, 2), -2)
- self.assertEqual(gcd(10, -2), 2)
- self.assertEqual(gcd(-10, -2), -2)
- for i in range(1, 20):
- for j in range(1, 20):
- self.assertTrue(gcd(i, j) > 0)
- self.assertTrue(gcd(-i, j) < 0)
- self.assertTrue(gcd(i, -j) > 0)
- self.assertTrue(gcd(-i, -j) < 0)
- def test_constructor(self):
- a = Rat(10, 15)
- self.assertEqual(a.num, 2)
- self.assertEqual(a.den, 3)
- a = Rat(10, -15)
- self.assertEqual(a.num, -2)
- self.assertEqual(a.den, 3)
- a = Rat(-10, 15)
- self.assertEqual(a.num, -2)
- self.assertEqual(a.den, 3)
- a = Rat(-10, -15)
- self.assertEqual(a.num, 2)
- self.assertEqual(a.den, 3)
- a = Rat(7)
- self.assertEqual(a.num, 7)
- self.assertEqual(a.den, 1)
- try:
- a = Rat(1, 0)
- except ZeroDivisionError:
- pass
- else:
- self.fail("Rat(1, 0) didn't raise ZeroDivisionError")
- for bad in "0", 0.0, 0j, (), [], {}, None, Rat, unittest:
- try:
- a = Rat(bad)
- except TypeError:
- pass
- else:
- self.fail("Rat(%r) didn't raise TypeError" % bad)
- try:
- a = Rat(1, bad)
- except TypeError:
- pass
- else:
- self.fail("Rat(1, %r) didn't raise TypeError" % bad)
- def test_add(self):
- self.assertEqual(Rat(2, 3) + Rat(1, 3), 1)
- self.assertEqual(Rat(2, 3) + 1, Rat(5, 3))
- self.assertEqual(1 + Rat(2, 3), Rat(5, 3))
- self.assertEqual(1.0 + Rat(1, 2), 1.5)
- self.assertEqual(Rat(1, 2) + 1.0, 1.5)
- def test_sub(self):
- self.assertEqual(Rat(7, 2) - Rat(7, 5), Rat(21, 10))
- self.assertEqual(Rat(7, 5) - 1, Rat(2, 5))
- self.assertEqual(1 - Rat(3, 5), Rat(2, 5))
- self.assertEqual(Rat(3, 2) - 1.0, 0.5)
- self.assertEqual(1.0 - Rat(1, 2), 0.5)
- def test_mul(self):
- self.assertEqual(Rat(2, 3) * Rat(5, 7), Rat(10, 21))
- self.assertEqual(Rat(10, 3) * 3, 10)
- self.assertEqual(3 * Rat(10, 3), 10)
- self.assertEqual(Rat(10, 5) * 0.5, 1.0)
- self.assertEqual(0.5 * Rat(10, 5), 1.0)
- def test_div(self):
- self.assertEqual(Rat(10, 3) / Rat(5, 7), Rat(14, 3))
- self.assertEqual(Rat(10, 3) / 3, Rat(10, 9))
- self.assertEqual(2 / Rat(5), Rat(2, 5))
- self.assertEqual(3.0 * Rat(1, 2), 1.5)
- self.assertEqual(Rat(1, 2) * 3.0, 1.5)
- def test_floordiv(self):
- self.assertEqual(Rat(10) // Rat(4), 2)
- self.assertEqual(Rat(10, 3) // Rat(4, 3), 2)
- self.assertEqual(Rat(10) // 4, 2)
- self.assertEqual(10 // Rat(4), 2)
- def test_eq(self):
- self.assertEqual(Rat(10), Rat(20, 2))
- self.assertEqual(Rat(10), 10)
- self.assertEqual(10, Rat(10))
- self.assertEqual(Rat(10), 10.0)
- self.assertEqual(10.0, Rat(10))
- def test_true_div(self):
- self.assertEqual(Rat(10, 3) / Rat(5, 7), Rat(14, 3))
- self.assertEqual(Rat(10, 3) / 3, Rat(10, 9))
- self.assertEqual(2 / Rat(5), Rat(2, 5))
- self.assertEqual(3.0 * Rat(1, 2), 1.5)
- self.assertEqual(Rat(1, 2) * 3.0, 1.5)
- self.assertEqual(eval('1/2'), 0.5)
- # XXX Ran out of steam; TO DO: divmod, div, future division
- class OperationLogger:
- """Base class for classes with operation logging."""
- def __init__(self, logger):
- self.logger = logger
- def log_operation(self, *args):
- self.logger(*args)
- def op_sequence(op, *classes):
- """Return the sequence of operations that results from applying
- the operation `op` to instances of the given classes."""
- log = []
- instances = []
- for c in classes:
- instances.append(c(log.append))
- try:
- op(*instances)
- except TypeError:
- pass
- return log
- class A(OperationLogger):
- def __eq__(self, other):
- self.log_operation('A.__eq__')
- return NotImplemented
- def __le__(self, other):
- self.log_operation('A.__le__')
- return NotImplemented
- def __ge__(self, other):
- self.log_operation('A.__ge__')
- return NotImplemented
- class B(OperationLogger, metaclass=ABCMeta):
- def __eq__(self, other):
- self.log_operation('B.__eq__')
- return NotImplemented
- def __le__(self, other):
- self.log_operation('B.__le__')
- return NotImplemented
- def __ge__(self, other):
- self.log_operation('B.__ge__')
- return NotImplemented
- class C(B):
- def __eq__(self, other):
- self.log_operation('C.__eq__')
- return NotImplemented
- def __le__(self, other):
- self.log_operation('C.__le__')
- return NotImplemented
- def __ge__(self, other):
- self.log_operation('C.__ge__')
- return NotImplemented
- class V(OperationLogger):
- """Virtual subclass of B"""
- def __eq__(self, other):
- self.log_operation('V.__eq__')
- return NotImplemented
- def __le__(self, other):
- self.log_operation('V.__le__')
- return NotImplemented
- def __ge__(self, other):
- self.log_operation('V.__ge__')
- return NotImplemented
- B.register(V)
- class OperationOrderTests(unittest.TestCase):
- def test_comparison_orders(self):
- self.assertEqual(op_sequence(eq, A, A), ['A.__eq__', 'A.__eq__'])
- self.assertEqual(op_sequence(eq, A, B), ['A.__eq__', 'B.__eq__'])
- self.assertEqual(op_sequence(eq, B, A), ['B.__eq__', 'A.__eq__'])
- # C is a subclass of B, so C.__eq__ is called first
- self.assertEqual(op_sequence(eq, B, C), ['C.__eq__', 'B.__eq__'])
- self.assertEqual(op_sequence(eq, C, B), ['C.__eq__', 'B.__eq__'])
- self.assertEqual(op_sequence(le, A, A), ['A.__le__', 'A.__ge__'])
- self.assertEqual(op_sequence(le, A, B), ['A.__le__', 'B.__ge__'])
- self.assertEqual(op_sequence(le, B, A), ['B.__le__', 'A.__ge__'])
- self.assertEqual(op_sequence(le, B, C), ['C.__ge__', 'B.__le__'])
- self.assertEqual(op_sequence(le, C, B), ['C.__le__', 'B.__ge__'])
- self.assertTrue(issubclass(V, B))
- self.assertEqual(op_sequence(eq, B, V), ['B.__eq__', 'V.__eq__'])
- self.assertEqual(op_sequence(le, B, V), ['B.__le__', 'V.__ge__'])
- class SupEq(object):
- """Class that can test equality"""
- def __eq__(self, other):
- return True
- class S(SupEq):
- """Subclass of SupEq that should fail"""
- __eq__ = None
- class F(object):
- """Independent class that should fall back"""
- class X(object):
- """Independent class that should fail"""
- __eq__ = None
- class SN(SupEq):
- """Subclass of SupEq that can test equality, but not non-equality"""
- __ne__ = None
- class XN:
- """Independent class that can test equality, but not non-equality"""
- def __eq__(self, other):
- return True
- __ne__ = None
- class FallbackBlockingTests(unittest.TestCase):
- """Unit tests for None method blocking"""
- def test_fallback_rmethod_blocking(self):
- e, f, s, x = SupEq(), F(), S(), X()
- self.assertEqual(e, e)
- self.assertEqual(e, f)
- self.assertEqual(f, e)
- # left operand is checked first
- self.assertEqual(e, x)
- self.assertRaises(TypeError, eq, x, e)
- # S is a subclass, so it's always checked first
- self.assertRaises(TypeError, eq, e, s)
- self.assertRaises(TypeError, eq, s, e)
- def test_fallback_ne_blocking(self):
- e, sn, xn = SupEq(), SN(), XN()
- self.assertFalse(e != e)
- self.assertRaises(TypeError, ne, e, sn)
- self.assertRaises(TypeError, ne, sn, e)
- self.assertFalse(e != xn)
- self.assertRaises(TypeError, ne, xn, e)
- if __name__ == "__main__":
- unittest.main()
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