{
 "metadata": {
  "name": "ch11"
 },
 "nbformat": 3,
 "nbformat_minor": 0,
 "worksheets": [
  {
   "cells": [
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.1\nAdding an Assignment Operator to the Ratio Class\nHere is a class interface for the Ratio class, showing the default constructor, the copy constructor,\nand the assignment operator:\n'''\nclass Ratio:\n    def __init__(self,n=None,d=None):\n        if d==None:\n            self.num = n.num\n            self.den = n.den\n        elif n==None:\n            self.num = 0\n            self.den = 1\n        else:\n            self.num = n\n            self.den = d\n        \n    def equals(self):\n        return self  # retuns calling object.",
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 1
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.2 The Preferred Prototype for an Overloaded Assignment Operator\n'''\nclass Ratio:\n    def __init__(self,n=None,d=None):\n        pass\n        \n    def equals(self):\n        pass\n",
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 2
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.3 Implementation of the Assignment Operator for the Ratio Class\n'''\nclass Ratio:\n    def __init__(self,n=None,d=None):\n        if d==None:\n            self.num = n.num\n            self.den = n.den\n        elif n==None:\n            self.num = 0\n            self.den = 1\n        else:\n            self.num = n\n            self.den = d\n        \n\nz = Ratio(22,7)\ny = z\nx = z\n\nx = Ratio(22,7)\ny = Ratio(x)\nz = x\nw = x",
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 3
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.4\nmultiplication operator overload\n'''\n\nclass Ratio:\n    def __init__(self,n=None,d=None):\n        self.num = n\n        self.den = d\n    def __mul__(self,y):\n        pass\n",
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 4
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.5 The Ratio Class with Assignment and Multiplication Operators\n'''\ndef gcd(m,n):\n    # returns the greatest common divisor of m and n:\n    if (m<n):\n        m,n = n,m\n    while (n>0):\n        r = m % n\n        m = n\n        n = r\n    return m\n\n\nclass Ratio:\n    def __init__(self,n=None,d=None):\n        self.num = n\n        self.den = d\n        self.reduce()\n    def __mul__(self,y):\n        z = Ratio(self.num * y.num, self.den * y.den)\n        return z\n    def print_(self):\n        print self.num , '/', self.den\n        \n    def reduce(self):\n        # enforce invariant(den > 0):\n        if (self.num == 0 or self.den == 0):\n            self.num = 0\n            self.den = 1\n            return\n        if (self.den < 0):\n            self.den *= -1\n            self.num *= -1\n        # enforce invariant(gcd(num,den) == 1):\n        if (self.den == 1):\n            return\n        # it's already reduced\n        sgn = 0\n        if self.num < 0:\n            sgn = -1\n        else:\n            sgn = 1\n        g = gcd(sgn*self.num,self.den)\n        self.num /= g\n        self.den /= g\nx = Ratio(22,7)\ny = Ratio(-3,8)\nz = x\nz.print_()\nx = y*z\nx.print_()\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "22 / 7\n-33 / 28\n"
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.6 The Ratio Class with an Overloaded *= Operator\n'''\ndef gcd(m,n):\n    # returns the greatest common divisor of m and n:\n    if (m<n):\n        m,n = n,m\n    while (n>0):\n        r = m % n\n        m = n\n        n = r\n    return m\n\n\nclass Ratio:\n    def __init__(self,n=None,d=None):\n        self.num = n\n        self.den = d\n        self.reduce()\n    def __imul__(self,y):\n        self.num = self.num * y.num\n        self.den = self.den * y.den\n    def print_(self):\n        print self.num , '/', self.den",
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 6
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.7 Overloading the Equality Operator == in the Ratio Class\n'''\n\nclass Ratio:\n    def __init__(self,n=None,d=None):\n        self.num = n\n        self.den = d\n        self.reduce()\n    def __imul__(self,y):\n        self.num = self.num * y.num\n        self.den = self.den * y.den\n    def __eq__(self,y):\n        return (x.num * y.den == y.num * x.den)\n    def print_(self):\n        print self.num , '/', self.den\n\n",
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 7
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.8 \nPython does not use << operator for printing. So here we are just declaring function name as print_.\n'''\n\nclass Ratio:\n    def __init__(self,n=None,d=None):\n        self.num = n\n        self.den = d\n    def __imul__(self,y):\n        self.num = self.num * y.num\n        self.den = self.den * y.den\n    def __eq__(self,y):\n        return (x.num * y.den == y.num * x.den)\n    def print_(self):\n        print self.num , '/', self.den\n\n\nx = Ratio(22,7)\ny = Ratio(-3,8)\nx.print_() ,  y.print_()\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "22 / 7\n-3 / 8\n"
      },
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 8,
       "text": "(None, None)"
      }
     ],
     "prompt_number": 8
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.9 \nPython does not have >> for input. so we will use input function.\n'''\ndef gcd(m,n):\n    # returns the greatest common divisor of m and n:\n    if (m<n):\n        m,n = n,m\n    while (n>0):\n        r = m % n\n        m = n\n        n = r\n    return m\nclass Ratio:\n    def __init__(self,n=0,d=1):\n        self.num = n\n        self.den = d\n        self.reduce()\n    def __mul__(self,y):\n        z = Ratio(self.num * y.num, self.den * y.den)\n        return z\n    def print_(self):\n        print self.num , '/', self.den\n        \n    def input(self):\n        self.num = int(raw_input('Numerator : '))\n        self.den = int(raw_input('Denominator : '))\n        self.reduce()\n    def reduce(self):\n        # enforce invariant(den > 0):\n        if (self.num == 0 or self.den == 0):\n            self.num = 0\n            self.den = 1\n            return\n        if (self.den < 0):\n            self.den *= -1\n            self.num *= -1\n        # enforce invariant(gcd(num,den) == 1):\n        if (self.den == 1):\n            return\n        # it's already reduced\n        sgn = 0\n        if self.num < 0:\n            sgn = -1\n        else:\n            sgn = 1\n        g = gcd(sgn*self.num,self.den)\n        self.num /= g\n        self.den /= g\n\n\nx = Ratio()\ny = Ratio()\nx.input()\ny.input()\nx.print_()\ny.print_()\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": "Numerator : -10\n"
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": "Denominator : -24\n"
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": "Numerator : 36\n"
      },
      {
       "name": "stdout",
       "output_type": "stream",
       "stream": "stdout",
       "text": "Denominator : -20\n"
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "5 / 12\n-9 / 5\n"
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.10\nAdding a Conversion Operator to the Ratio Class\n'''\ndef gcd(m,n):\n    # returns the greatest common divisor of m and n:\n    if (m<n):\n        m,n = n,m\n    while (n>0):\n        r = m % n\n        m = n\n        n = r\n    return m\nclass Ratio:\n    def __init__(self,n=0,d=1):\n        self.num = n\n        self.den = d\n        self.reduce()\n    def __mul__(self,y):\n        z = Ratio(self.num * y.num, self.den * y.den)\n        return z\n    def print_(self):\n        print self.num , '/', self.den\n        \n    def input(self):\n        self.num = int(raw_input('Numerator : '))\n        self.den = int(raw_input('Denominator : '))\n        self.reduce()\n    def __float__(self):\n        return float(self.num)/self.den\n    def reduce(self):\n        # enforce invariant(den > 0):\n        if (self.num == 0 or self.den == 0):\n            self.num = 0\n            self.den = 1\n            return\n        if (self.den < 0):\n            self.den *= -1\n            self.num *= -1\n        # enforce invariant(gcd(num,den) == 1):\n        if (self.den == 1):\n            return\n        # it's already reduced\n        sgn = 0\n        if self.num < 0:\n            sgn = -1\n        else:\n            sgn = 15.py\n        g = gcd(sgn*self.num,self.den)\n        self.num /= g\n        self.den /= g\n\nx = Ratio(-5,8)\nprint \"x = \" , \nx.print_() \nprint \", float(x) = \" , float(x) \nP = Ratio(22,7)\nPI = float(P)\nprint \"P = \" ,\nP.print_() \nprint \", PI = \" , PI\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "x =  -5 / 8\n, float(x) =  -0.625\nP =  22 / 7\n, PI =  3.14285714286\n"
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.11 Adding a Pre-Increment Operator to the Ratio Class\n'''\ndef gcd(m,n):\n    # returns the greatest common divisor of m and n:\n    if (m<n):\n        m,n = n,m\n    while (n>0):\n        r = m % n\n        m = n\n        n = r\n    return m\nclass Ratio:\n    def __init__(self,n=0,d=1):\n        self.num = n\n        self.den = d\n        self.reduce()\n    def __mul__(self,y):\n        z = Ratio(self.num * y.num, self.den * y.den)\n        return z\n    def print_(self):\n        print self.num , '/', self.den\n        \n    def __iadd__(self,n):\n        self.num += self.den\n        return self\n    def reduce(self):\n        # enforce invariant(den > 0):\n        if (self.num == 0 or self.den == 0):\n            self.num = 0\n            self.den = 1\n            return\n        if (self.den < 0):\n            self.den *= -1\n            self.num *= -1\n        # enforce invariant(gcd(num,den) == 1):\n        if (self.den == 1):\n            return\n        # it's already reduced\n        sgn = 0\n        if self.num < 0:\n            sgn = -1\n        else:\n            sgn = 1\n        g = gcd(sgn*self.num,self.den)\n        self.num /= g\n        self.den /= g\n\nx = Ratio(22,7)\nx += 1\ny = x\nprint \"y = \" ,\ny.print_()\nprint \", x = \",\nx.print_()\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "y =  29 / 7\n, x =  29 / 7\n"
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.12 Adding a Post-Increment Operator to the Ratio Class\n'''\ndef gcd(m,n):\n    # returns the greatest common divisor of m and n:\n    if (m<n):\n        m,n = n,m\n    while (n>0):\n        r = m % n\n        m = n\n        n = r\n    return m\nclass Ratio:\n    def __init__(self,n=0,d=1):\n        self.num = n\n        self.den = d\n        self.reduce()\n    def __mul__(self,y):\n        z = Ratio(self.num * y.num, self.den * y.den)\n        return z\n    def print_(self):\n        print self.num , '/', self.den\n        \n    def __iadd__(self,n):\n        self.num += self.den\n        return self\n    def reduce(self):\n        # enforce invariant(den > 0):\n        if (self.num == 0 or self.den == 0):\n            self.num = 0\n            self.den = 1\n            return\n        if (self.den < 0):\n            self.den *= -1\n            self.num *= -1\n        # enforce invariant(gcd(num,den) == 1):\n        if (self.den == 1):\n            return\n        # it's already reduced\n        sgn = 0\n        if self.num < 0:\n            sgn = -1\n        else:\n            sgn = 1\n        g = gcd(sgn*self.num,self.den)\n        self.num /= g\n        self.den /= g\n\nx = Ratio(22,7)\ny = Ratio(x.num,x.den)\nx += 1\nprint \"y = \" ,\ny.print_()\nprint \", x = \",\nx.print_()\n\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "y =  22 / 7\n, x =  29 / 7\n"
      }
     ],
     "prompt_number": 9
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "'''\nEXAMPLE 11.13\nAdding a Subscript Operator to the Ratio Class\n'''\ndef gcd(m,n):\n    # returns the greatest common divisor of m and n:\n    if (m<n):\n        m,n = n,m\n    while (n>0):\n        r = m % n\n        m = n\n        n = r\n    return m\nclass Ratio:\n    def __init__(self,n=0,d=1):\n        self.num = n\n        self.den = d\n        self.reduce()\n    def __mul__(self,y):\n        z = Ratio(self.num * y.num, self.den * y.den)\n        return z\n    def print_(self):\n        print self.num , '/', self.den\n        \n    def __getitem__(self,k):\n        if k == 1:\n            return  self.num\n        else:\n            return self.den\n    def reduce(self):\n        # enforce invariant(den > 0):\n        if (self.num == 0 or self.den == 0):\n            self.num = 0\n            self.den = 1\n            return\n        if (self.den < 0):\n            self.den *= -1\n            self.num *= -1\n        # enforce invariant(gcd(num,den) == 1):\n        if (self.den == 1):\n            return\n        # it's already reduced\n        sgn = 0\n        if self.num < 0:\n            sgn = -1\n        else:\n            sgn = 1\n        g = gcd(sgn*self.num,self.den)\n        self.num /= g\n        self.den /= g\n\nx = Ratio(22,7)\nprint \"x = \" ,\nx.print_()\nprint \"x[1] = \" , x[1] , \", x[2] = \" , x[2]\n",
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": "x =  22 / 7\nx[1] =  22 , x[2] =  7\n"
      }
     ],
     "prompt_number": 7
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": "",
     "language": "python",
     "metadata": {},
     "outputs": []
    }
   ],
   "metadata": {}
  }
 ]
}