'''A simple class for representing fractions.

Jeff Ondich, 10 Dec 2006

Each object of class Fraction represents a single fraction.  This
class is intended as an illustration of a few simple properties
of Python classes--not as a complete implementation of the notion
of a fraction.
'''

class Fraction:
    def __init__(self, num, denom):
        self.numerator = num
        self.denominator = denom

    def __str__(self):
        return '%d/%d' % (self.numerator, self.denominator)


    def __add__(self, other):
        '''
        Returns a new Fraction object containing the sum of this Fraction
        and the Fraction object other.
        '''
        num = self.numerator * other.denominator + other.numerator * self.denominator
        denom = self.denominator * other.denominator
        newFraction = Fraction(num, denom)
        newFraction.reduce()
        return newFraction

    def add(self, other):
        '''
        Adds the Fraction object "other" to the Fraction object self.
        '''
        self.numerator = self.numerator * other.denominator + other.numerator * self.denominator
        self.denominator = self.denominator * other.denominator
        self.reduce()

    def subtract(self, other):
        '''
        Subtracts the Fraction object "other" from the Fraction object self.
        '''
        self.numerator = self.numerator * other.denominator - other.numerator * self.denominator
        self.denominator = self.denominator * other.denominator
        self.reduce()

    def multiply(self, other):
        '''
        Multiplies this Fraction object by the Fraction object "other".
        '''
        self.numerator = self.numerator * other.numerator
        self.denominator = self.denominator * other.denominator
        self.reduce()

    def reduce(self):
        '''
        Reduces this Fraction.  After calling reduce() on a Fraction
        object, the fraction will be in lowest terms (that is, its
        numerator and denominator will be relatively prime).
        '''
        factor = min(self.numerator, self.denominator)
        while factor >= 1:
            if self.numerator % factor == 0 and self.denominator % factor == 0:
                self.numerator = self.numerator / factor
                self.denominator = self.denominator / factor
                return
            factor = factor - 1


if __name__ == '__main__':
    f = Fraction(117, 18)
    print 'Here is a fraction:', f
    f.reduce()
    print 'Here is the same fraction in lowest terms:', f
    print

    a = Fraction(5, 6)
    b = Fraction(4, 5)
    sum = a + b
    print 'Adding fractions:', a, '+', b, '=', sum
    
    print 'Multiplying fractions:', a, '*', b, '=',
    a.multiply(b)
    print a