cpython/Demo/classes/Rat.py

98 lines
1.7 KiB
Python
Executable File

# Rational numbers
def rat(num, den):
return Rat(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
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
if t == type(a) and a.__class__ == b.__class__:
return a, b
raise TypeError, 'Rat.__coerce__: bad other arg'
def __add__(a, b):
if type(b) <> type(a):
a, b = a.__coerce__(b)
return 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):
if type(b) <> type(a):
a, b = a.__coerce__(b)
return 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 a+1
print a+1L
print a+1.0
try:
print rat(1, 0)
raise SystemError, 'should have been ZeroDivisionError'
except ZeroDivisionError:
print 'OK'
test()