{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "# Objects in Python"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Everything in Python is an 'object'.\n",
        "\n",
        "Defining custom types of objects is easy:"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 1,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "\n",
        "class Employee:\n",
        "    def __init__(self, name, salary):\n",
        "        self.name = name\n",
        "        self.salary = salary\n",
        "        \n",
        "    def fire(self):\n",
        "        self.salary = 0"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "* Functions within the class (type) definition are called 'methods'.\n",
        "* They take an explicit `self` parameter, through which the object is passed.\n",
        "* `__init__` is the 'constructor'\n",
        "    * Objects are created by 'calling' the type like a function.\n",
        "    * Arguments in this call are passed to the constructor"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 11,
      "metadata": {
        "collapsed": false
      },
      "outputs": [
        {
          "data": {
            "text/plain": [
              "'Joe'"
            ]
          },
          "execution_count": 11,
          "metadata": {},
          "output_type": "execute_result"
        }
      ],
      "source": [
        "joe = Employee(\"Joe\", 100000)\n",
        "joe.name"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 7,
      "metadata": {
        "collapsed": false
      },
      "outputs": [
        {
          "data": {
            "text/plain": [
              "100000"
            ]
          },
          "execution_count": 7,
          "metadata": {},
          "output_type": "execute_result"
        }
      ],
      "source": [
        "joe.salary"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Let's fire Joe."
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 8,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "joe.fire()"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 9,
      "metadata": {
        "collapsed": false
      },
      "outputs": [
        {
          "data": {
            "text/plain": [
              "0"
            ]
          },
          "execution_count": 9,
          "metadata": {},
          "output_type": "execute_result"
        }
      ],
      "source": [
        "joe.salary"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "## Inheritance"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Types can be based on other types by inheritance:"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 10,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "class Boss(Employee):\n",
        "    def __init__(self, name, salary, supervises):\n",
        "        super(Boss, self).__init__(name, salary)\n",
        "        \n",
        "        self.supervises = supervises\n",
        "        \n",
        "    def fire(self):\n",
        "        for s in self.supervises:\n",
        "            s.fire()\n",
        "            \n",
        "        super(Boss, self).fire()"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 12,
      "metadata": {
        "collapsed": false
      },
      "outputs": [
        {
          "data": {
            "text/plain": [
              "150000"
            ]
          },
          "execution_count": 12,
          "metadata": {},
          "output_type": "execute_result"
        }
      ],
      "source": [
        "joe = Employee(\"Joe\", 100000)\n",
        "jack = Employee(\"Jack\", 100000)\n",
        "mike = Boss(\"Mike\", 150000, [joe, jack])\n",
        "\n",
        "mike.salary"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 13,
      "metadata": {
        "collapsed": false
      },
      "outputs": [
        {
          "data": {
            "text/plain": [
              "100000"
            ]
          },
          "execution_count": 13,
          "metadata": {},
          "output_type": "execute_result"
        }
      ],
      "source": [
        "joe.salary"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Now what happens to Joe's salary if Mike gets fired?"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 14,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "mike.fire()"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": 15,
      "metadata": {
        "collapsed": false
      },
      "outputs": [
        {
          "data": {
            "text/plain": [
              "0"
            ]
          },
          "execution_count": 15,
          "metadata": {},
          "output_type": "execute_result"
        }
      ],
      "source": [
        "joe.salary"
      ]
    }
  ],
  "metadata": {},
  "nbformat": 4,
  "nbformat_minor": 0
}