{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Factory Pattern\n",
    "1. A Creational pattern\n",
    "1. One Api to create different objects\n",
    "1. Also known as Virtual Constructor"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Car Factory"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "from abc import ABCMeta, abstractmethod"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Interfaces"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "class IAuto(metaclass=ABCMeta):\n",
    "    @abstractmethod\n",
    "    def start(self):\n",
    "        pass\n",
    "\n",
    "    @abstractmethod\n",
    "    def stop(self):\n",
    "        pass"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class IFactory(metaclass=ABCMeta):\n",
    "    @abstractmethod\n",
    "    def create_auto(self):\n",
    "        pass"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Tesla Factory"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class Tesla(IAuto):\n",
    "    def __init__(self, car_name):\n",
    "        self._carname = car_name\n",
    "\n",
    "    def start(self):\n",
    "        print(f\"{self._carname} barely makes any noise.\")\n",
    "\n",
    "    def stop(self):\n",
    "        print(f\"{self._carname} stops within moments\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class TeslaFactory(IFactory):\n",
    "    def create_auto(self):\n",
    "        self.tesla = Tesla('Tesla Model S')\n",
    "        return self.tesla"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Dodge Factory"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class DodgeSRT(IAuto):\n",
    "    def __init__(self, car_name):\n",
    "        self._carname = car_name\n",
    "\n",
    "    def start(self):\n",
    "        print(f\"{self._carname} Growls\")\n",
    "\n",
    "    def stop(self):\n",
    "        print(f\"{self._carname} Screeches to a stop!\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class DodgeFactory(IFactory):\n",
    "    def create_auto(self):\n",
    "        self.dodge_srt = DodgeSRT('Dodge SRT')\n",
    "        return self.dodge_srt"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Null Factory"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class NullCar(IAuto):\n",
    "    def __init__(self, car_name):\n",
    "        self._carname = car_name\n",
    "\n",
    "    def start(self):\n",
    "        print(f'Unknown Vehichle {self._carname}')\n",
    "\n",
    "    def stop(self):\n",
    "        print(f'Vehicle Stopped')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class NullFactory(IFactory):\n",
    "    def create_auto(self):\n",
    "        self.null_car = NullCar('')\n",
    "        return self.null_car"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Simple Auto Factory"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class AutoFactory():\n",
    "    autos = {}\n",
    "\n",
    "    def __init__(self):\n",
    "        self.load_autos()\n",
    "\n",
    "    def load_autos(self):\n",
    "        self.autos.update([[Tesla.__name__, Tesla],\n",
    "                           [DodgeSRT.__name__, DodgeSRT],\n",
    "                           [NullCar.__name__, NullCar]]);\n",
    "\n",
    "    def create_instance(self, car_name):\n",
    "        if car_name in self.autos:\n",
    "            return self.autos[car_name](car_name)\n",
    "        else:\n",
    "            return self.autos['NullCar'](car_name)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "DodgeSRT Growls\n",
      "DodgeSRT Screeches to a stop!\n",
      "----------------\n",
      "Tesla barely makes any noise.\n",
      "Tesla stops within moments\n",
      "----------------\n",
      "Unknown Vehichle Chevrolet\n",
      "Vehicle Stopped\n",
      "----------------\n"
     ]
    }
   ],
   "source": [
    "factory = AutoFactory()\n",
    "\n",
    "for car_name in 'DodgeSRT', 'Tesla', 'Chevrolet':\n",
    "    car = factory.create_instance(car_name)\n",
    "\n",
    "    car.start()\n",
    "    car.stop()\n",
    "    print('----------------')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Sophisticated Auto Factory"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {
    "collapsed": true
   },
   "outputs": [],
   "source": [
    "class FactoryManager():\n",
    "    factories = {}\n",
    "\n",
    "    def __init__(self):\n",
    "        self.load_factories()\n",
    "\n",
    "    def load_factories(self):\n",
    "        self.factories.update([[TeslaFactory.__name__, TeslaFactory],\n",
    "                               [DodgeFactory.__name__, DodgeFactory],\n",
    "                               [NullFactory.__name__, NullFactory]]);\n",
    "\n",
    "    def create_factory(self, factory_name):\n",
    "        if factory_name in self.factories:\n",
    "            return self.factories[factory_name]()\n",
    "        else:\n",
    "            return self.factories['NullFactory']()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Dodge SRT Growls\n",
      "Dodge SRT Screeches to a stop!\n",
      "----------------\n",
      "Tesla Model S barely makes any noise.\n",
      "Tesla Model S stops within moments\n",
      "----------------\n",
      "Unknown Vehichle \n",
      "Vehicle Stopped\n",
      "----------------\n"
     ]
    }
   ],
   "source": [
    "factory_manager = FactoryManager()\n",
    "\n",
    "for factory_name in 'DodgeFactory', 'TeslaFactory', 'ChevroletFactory':\n",
    "    factory = factory_manager.create_factory(factory_name)\n",
    "    car = factory.create_auto()\n",
    "\n",
    "    car.start()\n",
    "    car.stop()\n",
    "    print('----------------')"
   ]
  }
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