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  {
   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h1>Chapter 12: A Closer Look at Classes<h1>"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.1, Page Number: 274<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "class myclass:\n",
      "    __a=None\n",
      "    __b=None\n",
      "    def __init__(self,i,j):\n",
      "        self.__a=i\n",
      "        self.__b=j\n",
      "    def sum(self,x):   #Friend function\n",
      "        return sum1(x)\n",
      "        \n",
      "def sum1(x):        \n",
      "    return x._myclass__a +x._myclass__b   #accessing private members\n",
      "\n",
      "#Variable declaration\n",
      "n=myclass(3,4)\n",
      "\n",
      "#Result\n",
      "print n.sum(n)\n",
      "\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "7\n"
       ]
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.2, Page Number: 275<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "class c1:\n",
      "    __status=None\n",
      "    def set_status(self,state):\n",
      "        self.__status=state\n",
      "    \n",
      "class c2:\n",
      "    __status=None\n",
      "    def set_status(self,state):\n",
      "        self.status=state\n",
      "    \n",
      "#Friend function    \n",
      "def idle(a,b):\n",
      "    if a._c1__status or b._c2__status :\n",
      "        return 0\n",
      "    else:\n",
      "        return 1\n",
      "    \n",
      "#variable declarations\n",
      "def IDLE():             #Constants\n",
      "    return 0\n",
      "def INUSE():\n",
      "    return 1\n",
      "x=c1()\n",
      "y=c2()\n",
      "\n",
      "x.set_status(IDLE())\n",
      "y.set_status(IDLE())\n",
      "\n",
      "if idle(x,y):\n",
      "    print \"Screen Can Be Used.\"\n",
      "    \n",
      "x.set_status(INUSE())\n",
      "\n",
      "if idle(x,y):\n",
      "    print \"Screen Can Be Used.\"\n",
      "else:\n",
      "    print \"Pop-up In Use.\"\n",
      "    \n",
      "    "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Screen Can Be Used.\n",
        "Pop-up In Use.\n"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.3, Page Number: 277<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "def IDLE():            \n",
      "    return 0\n",
      "def INUSE():\n",
      "    return 1\n",
      "\n",
      "class c1:\n",
      "    __status=None\n",
      "    def set_status(self,state):\n",
      "        self.__status=state\n",
      "    def idle(self,b):            #now a member of c1\n",
      "        if self.__status or b._c2__status :\n",
      "            return 0\n",
      "        else:\n",
      "            return 1\n",
      "    \n",
      "class c2:\n",
      "    __status=None     #IDLE if off INUSE if on screen\n",
      "    def set_status(self,state):\n",
      "        self.status=state\n",
      "        \n",
      "#Variable declarations        \n",
      "x=c1()\n",
      "y=c2()\n",
      "\n",
      "x.set_status(IDLE())\n",
      "y.set_status(IDLE())\n",
      "\n",
      "if idle(x,y):\n",
      "    print \"Screen Can Be Used.\"\n",
      "    \n",
      "x.set_status(INUSE())\n",
      "\n",
      "if idle(x,y):\n",
      "    print \"Screen Can Be Used.\"\n",
      "else:\n",
      "    print \"Pop-up In Use.\"\n",
      "        "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Screen Can Be Used.\n",
        "Pop-up In Use.\n"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.4, Page Number: 278<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "import time,string\n",
      "\n",
      "class timer:\n",
      "    __seconds=None\n",
      "    \n",
      "    def __init__(self,t1,t2=None):\n",
      "        if t2==None:\n",
      "            if isinstance(t1,int):   #seconds specified as an integer\n",
      "                self.__seconds=t1\n",
      "            else:                    #seconds specified as a string\n",
      "                self.__seconds=string.atoi(t1)\n",
      "        else:                        #time in minutes and seconds\n",
      "            self.__seconds=t1*60+t2\n",
      "            \n",
      "    def run(self):\n",
      "        t1=time.clock()\n",
      "        while (time.clock()-t1)<self.__seconds:\n",
      "            a=10\n",
      "        print time.clock()-t1\n",
      " \n",
      "        \n",
      "a=timer(10)\n",
      "b=timer(\"20\")\n",
      "c=timer(1,10)\n",
      "a.run()            #count 10 seconds\n",
      "b.run()            #count 20 seconds\n",
      "c.run()            #count 1 minute,10 seconds\n",
      "        "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10.0000009774\n",
        "20.0000009774"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "70.0000004887"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n"
       ]
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.5, Page Number: 280<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "import time,string\n",
      "\n",
      "class timer:\n",
      "    __seconds=None\n",
      "    \n",
      "    def __init__(self,t1,t2=None):\n",
      "        if t2==None:\n",
      "            if isinstance(t1,int):   #seconds specified as an integer\n",
      "                self.__seconds=t1\n",
      "            else:                    #seconds specified as a string\n",
      "                self.__seconds=string.atoi(t1)\n",
      "        else:                        #time in minutes and seconds\n",
      "            self.__seconds=t1*60+t2\n",
      "            \n",
      "    def run(self):\n",
      "        t1=time.clock()\n",
      "        while (time.clock()-t1)<self.__seconds:\n",
      "            a=10\n",
      "        print time.clock()-t1\n",
      "            \n",
      "a=timer(10)\n",
      "a.run()\n",
      "\n",
      "print \"Enter number of seconds: \"\n",
      "str=\"20\"\n",
      "b=timer(str)                       #initialize at the run time\n",
      "c.run()\n",
      "\n",
      "print \"Enter minutes and seconds: \"\n",
      "min=1\n",
      "sec=10\n",
      "c=timer(min,sec)                   #initialize at the run time\n",
      "c.run()\n",
      "        "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10.0000004887\n",
        "Enter number of seconds: \n",
        "70.0000009774"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n",
        "Enter minutes and seconds: \n",
        "70.0000009774"
       ]
      },
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "\n"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.6, Page Number: 282<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "class myclass:\n",
      "    __a=None             #private members\n",
      "    __b=None\n",
      "    def setab(self,i,j): #publc functons\n",
      "        self.__a=i\n",
      "        self.__b=j\n",
      "    def showab(self):\n",
      "        print \"a is \",self.__a\n",
      "        print \"b is \",self.__b\n",
      "\n",
      "#Variable declaration\n",
      "ob1 = myclass()\n",
      "ob2 = myclass()\n",
      "\n",
      "#Intalizing\n",
      "ob1.setab(10,20)\n",
      "ob2.setab(0,0)\n",
      "\n",
      "print \"ob1 before assignment: \"\n",
      "ob1.showab()\n",
      "print \"ob2 before assignment: \"\n",
      "ob2.showab()\n",
      "\n",
      "ob2 = ob1            #assign ob1 to ob2\n",
      "\n",
      "#Result\n",
      "print \"ob1 after assignment: \"\n",
      "ob1.showab()\n",
      "print \"ob2 after assignment: \"\n",
      "ob2.showab()\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "ob1 before assignment: \n",
        "a is  10\n",
        "b is  20\n",
        "ob2 before assignment: \n",
        "a is  0\n",
        "b is  0\n",
        "ob1 after assignment: \n",
        "a is  10\n",
        "b is  20\n",
        "ob2 after assignment: \n",
        "a is  10\n",
        "b is  20\n"
       ]
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.7, Page Number: 283<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "from copy import deepcopy\n",
      "        \n",
      "class OBJ:\n",
      "    def set_i(self,x):\n",
      "        self.__i=x\n",
      "    def out_i(self):\n",
      "        print self.__i,\n",
      "    \n",
      "def f(x):\n",
      "    x=deepcopy(x)\n",
      "    x.out_i()     #outputs 10\n",
      "    x.set_i(100)  #this affects only local copy\n",
      "    x.out_i()     #outputs 100\n",
      "    \n",
      "#Variable declaration\n",
      "o=OBJ()\n",
      "o.set_i(10)\n",
      "f(o)               \n",
      "o.out_i()         #still outputs 10, value of i unchanged\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10 100 10\n"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.8, Page Number: 284<h3> "
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "class myclass:                       \n",
      "    def __init__(self,i):\n",
      "        self.__val=i\n",
      "        print \"Constructing\"\n",
      "    def __del__(self):\n",
      "        print \"Destructing\"\n",
      "    def getval(self):\n",
      "        return self.__val\n",
      "        \n",
      "def display(ob):\n",
      "    print ob.getval()\n",
      "\n",
      "#Varable declaration\n",
      "a=myclass(10)\n",
      "\n",
      "display(a)\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Constructing\n",
        "Destructing\n",
        "10\n"
       ]
      }
     ],
     "prompt_number": 2
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.9, Page Number: 286<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "from ctypes import *\n",
      "\n",
      "class myclass:\n",
      "    def __init__(self,i):\n",
      "        print \"Allocating p\"\n",
      "        self.p=pointer(c_int(i))\n",
      "    def __del__(self):\n",
      "        print \"Freeing p\"\n",
      "    def getval(self):\n",
      "        return self.p[0]\n",
      "        \n",
      "def display(ob):\n",
      "    print ob.getval()\n",
      "\n",
      "#Variable declaration\n",
      "a=myclass(10)\n",
      "\n",
      "display(a)\n",
      "    "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Allocating p\n",
        "10\n"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.10, Page Number: 287<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "'''Passing objects by reference'''\n",
      "\n",
      "from ctypes import *\n",
      "class myclass:\n",
      "    def __init__(self,i):\n",
      "        print \"Allocating p\"\n",
      "        self.p=pointer(c_int(i))\n",
      "    def __del__(self):\n",
      "        print \"Freeing p\"\n",
      "    def getval(self):\n",
      "        return self.p[0]\n",
      "        \n",
      "def display(ob):\n",
      "    print ob[0].getval()\n",
      "\n",
      "#Variable declaration\n",
      "a=[]\n",
      "a.append(myclass(10))\n",
      "\n",
      "display(a)\n",
      "    "
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Freeing p\n",
        "Allocating p\n",
        "10\n"
       ]
      }
     ],
     "prompt_number": 5
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.11, Page Number: 288<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "class sample:\n",
      "    __s=None\n",
      "    def show(self):\n",
      "        print self.__s\n",
      "    def set(self,str):\n",
      "        self.__s=str\n",
      "\n",
      "#Return an object of type sample\n",
      "def input():\n",
      "    str=sample()\n",
      "    instr = \"Hello\"       #User input\n",
      "    str.set(instr)\n",
      "    return str\n",
      "\n",
      "#Variable declaration\n",
      "ob=sample()\n",
      "\n",
      "#assign returned object to ob\n",
      "ob=input()\n",
      "\n",
      "#Result\n",
      "ob.show()\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Hello\n"
       ]
      }
     ],
     "prompt_number": 6
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.12, Page Number: 289<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "#\n",
      "class sample:\n",
      "    __s=None\n",
      "    def __init__(self):\n",
      "        self.__s=0\n",
      "    def __del__(self):          \n",
      "        print \"Freeing p\"\n",
      "    def show(self):\n",
      "        print self.__s\n",
      "    def set(self,str):\n",
      "        self.__s=str\n",
      "        \n",
      "#This function takes one object parameter\n",
      "def input():\n",
      "    str=sample()\n",
      "    instr=\"Hello\"    #User input\n",
      "    str.set(instr)\n",
      "    return str\n",
      "\n",
      "#Variable declaration\n",
      "ob=sample()\n",
      "\n",
      "#assign returned object to ob\n",
      "ob=input()\n",
      "\n",
      "#Result\n",
      "ob.show()\n",
      "\n",
      "\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Freeing p\n",
        "Freeing p\n",
        "Hello\n"
       ]
      }
     ],
     "prompt_number": 8
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.13, Page Number: 292<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "class myclass:\n",
      "    __p=None\n",
      "    def __init__(self,i):\n",
      "        if isinstance(i,int):\n",
      "            print \"Allocating p\"\n",
      "            self.__p=i\n",
      "        else:\n",
      "            print \"Copy constructor called\"\n",
      "            self.__p=i.getval()\n",
      "    def __del__(self):          \n",
      "        print \"Freeing p\"\n",
      "    def getval(self):\n",
      "        return self.__p\n",
      "        \n",
      "#This function takes one object parameter\n",
      "def display(ob):\n",
      "    print ob.getval()\n",
      "\n",
      "#Variable declaration\n",
      "ob=myclass(10)\n",
      "\n",
      "#Result\n",
      "display(ob)\n",
      "\n",
      "\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Allocating p\n",
        "10\n"
       ]
      }
     ],
     "prompt_number": 1
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.14, Page Number: 294<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "\n",
      "class myclass:\n",
      "    __p=None\n",
      "    def __init__(self,i):\n",
      "        if isinstance(i,int):\n",
      "            print \"Allocating p\"\n",
      "            self.__p=i\n",
      "        else:\n",
      "            print \"Copy constructor called\"\n",
      "            self.__p=i.getval()\n",
      "    def __del__(self):          \n",
      "        print \"Freeing p\"\n",
      "    def getval(self):\n",
      "        return self.__p\n",
      "        \n",
      "\n",
      "#Variable declaration\n",
      "a=myclass(10)         #calls normal constructor\n",
      "b=myclass(a)           #calls copy constructor\n",
      "\n",
      "\n",
      "\n",
      "\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Allocating p\n",
        "Copy constructor called\n"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.15, Page Number: 295<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "class myclass:\n",
      "    def __init__(self,i=0):\n",
      "        if isinstance(i,int):\n",
      "            print \"Normal constructor\"\n",
      "        else:\n",
      "            print \"Copy constructor\"\n",
      "\n",
      "\n",
      "#Variable declaration\n",
      "a=myclass()           #calls normal constructor\n",
      "\n",
      "f=myclass()\n",
      "a=myclass(f)          #Invoke copyconstructor\n",
      "\n",
      "\n",
      "\n",
      "\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "Normal constructor\n",
        "Normal constructor\n",
        "Copy constructor\n"
       ]
      }
     ],
     "prompt_number": 8
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "<h3>Example 12.16, Page Number: 297<h3>"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "\n",
      "\n",
      "class c1:\n",
      "    def __init__(self):\n",
      "        self.__i=None\n",
      "    def load_i(self,val):\n",
      "        self.__i=val\n",
      "    def get_i(self):\n",
      "        return self.__i\n",
      "    \n",
      "#Variable declaration    \n",
      "o=c1()\n",
      "\n",
      "o.load_i(100)\n",
      "\n",
      "#Result\n",
      "print o.get_i()\n"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "100\n"
       ]
      }
     ],
     "prompt_number": 13
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [],
     "language": "python",
     "metadata": {},
     "outputs": []
    }
   ],
   "metadata": {}
  }
 ]
}