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   "source": [
    "# 1. Inheritance\n",
    "\n",
    "\n",
    "In OOP, one can also create a class that is based on another class. \n",
    "\n",
    "* The parent class is called the **superclass**\n",
    "* The new, child class is called the **subclass**\n",
    "\n",
    "In this example, we make a **base class** `Animal` to serve as the superclass of a subclass `Dog`.\n",
    "\n",
    "We say that a Dog **is-a** Animal.\n",
    "\n",
    "For **has-a** relationships, we make those properties of the class (like has-a name)."
   ]
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  {
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   "execution_count": 1,
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     "text": [
      "|  Added class Animal\n",
      "\n"
     ]
    }
   ],
   "source": [
    "class Animal {\n",
    "    public void speak() {\n",
    "        printf(\"I am an animal\\n\");\n",
    "    }\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
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   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "|  Added variable animal of type Animal with initial value Animal@44e81672\n",
      "\n"
     ]
    }
   ],
   "source": [
    "Animal animal = new Animal();"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "I am an animal\n",
      "\n"
     ]
    }
   ],
   "source": [
    "animal.speak();"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "|  Added class Dog\n",
      "\n"
     ]
    }
   ],
   "source": [
    "class Dog extends Animal {\n",
    "    public void speak() {\n",
    "        printf(\"woof!\\n\");\n",
    "    }    \n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
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   "outputs": [
    {
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     "text": [
      "|  Added variable dog of type Dog with initial value Dog@2471cca7\n",
      "\n"
     ]
    }
   ],
   "source": [
    "Dog dog = new Dog();"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "woof!\n",
      "\n"
     ]
    }
   ],
   "source": [
    "dog.speak();"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "|  Added variable whatisthis of type Animal with initial value Dog@2471cca7\n",
      "\n"
     ]
    }
   ],
   "source": [
    "Animal whatisthis = dog;"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "woof!\n",
      "\n"
     ]
    }
   ],
   "source": [
    "whatisthis.speak();"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The Dog object gets the message \"speak\" and it has a method for that. \n",
    "\n",
    "This is called **Polymorphism**.\n",
    "\n",
    "*See Page 19 of your textbook for more details.*"
   ]
  }
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