Initial revision

Demo/classes/Rat.py

@@ -0,0 +1,86 @@
+# Rational numbers
+
+
+def rat(num, den):
+	return Rat().init(num, den)
+
+
+def gcd(a, b):
+	while b:
+		a, b = b, a%b
+	return a
+
+
+class Rat:
+
+	def init(self, num, den):
+		if den == 0:
+			raise ZeroDivisionError, 'rat(x, 0)'
+		g = gcd(num, den)
+		self.num = num/g
+		self.den = den/g
+		return self
+
+	def __repr__(self):
+		return 'rat' + `self.num, self.den`
+
+	def __cmp__(a, b):
+		c = a-b
+		if c.num < 0:
+			return -1
+		if c.num > 0:
+			return 1
+		return 0
+
+	def __float__(self):
+		return float(self.num) / float(self.den)
+
+	def __long__(self):
+		return long(self.num) / long(self.den)
+
+	def __int__(self):
+		return int(self.num / self.den)
+
+	def __coerce__(a, b):
+		t = type(b)
+		if t == type(0):
+			return a, rat(b, 1)
+		if t == type(0L):
+			return a, rat(b, 1L)
+		if t == type(0.0):
+			return a.__float__(), b
+		raise TypeError, 'Rat.__coerce__: bad other arg'
+			
+	def __add__(a, b):
+		return rat(a.num*b.den + b.num*a.den, a.den*b.den)
+
+	def __sub__(a, b):
+		return rat(a.num*b.den - b.num*a.den, a.den*b.den)
+
+	def __mul__(a, b):
+		return rat(a.num*b.num, a.den*b.den)
+
+	def __div__(a, b):
+		return rat(a.num*b.den, a.den*b.num)
+
+	def __neg__(self):
+		return rat(-self.num, self.den)
+
+
+def test():
+	print rat(-1L, 1)
+	print rat(1, -1)
+	a = rat(1, 10)
+	print int(a), long(a), float(a)
+	b = rat(2, 5)
+	l = [a+b, a-b, a*b, a/b]
+	print l
+	l.sort()
+	print l
+	print rat(0, 1)
+	print rat(1, 0)
+	print a+1
+	print a+1L
+	print a+1.0
+
+test()