Factory Method Design Pattern in Python and it's Implementations

classic.ipynb

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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Factory Design Patterns and it's Implementation in Python"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Example is based on article from https://realpython.com/factory-method-python/"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "# pip install pyyaml"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "import json\n",
    "import xml.etree.ElementTree as et\n",
    "import yaml"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "class Song:\n",
    "    def __init__(self, song_id, title, artist):\n",
    "        self.song_id = song_id\n",
    "        self.title = title\n",
    "        self.artist = artist"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "class Song:\n",
    "    def __init__(self, song_id, title, artist):\n",
    "        self.song_id = song_id\n",
    "        self.title = title\n",
    "        self.artist = artist\n",
    "\n",
    "    def serialize(self, serializer):\n",
    "        serializer.start_object('song', self.song_id)\n",
    "        serializer.add_property('title', self.title)\n",
    "        serializer.add_property('artist', self.artist)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "class ObjectSerializer:\n",
    "    def serialize(self, serializable, format):\n",
    "        serializer = factory.get_serializer(format)\n",
    "        serializable.serialize(serializer)\n",
    "        return serializer.to_str()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [],
   "source": [
    "class JsonSerializer:\n",
    "    def __init__(self):\n",
    "        self._current_object = None\n",
    "\n",
    "    def start_object(self, object_name, object_id):\n",
    "        self._current_object = {\n",
    "            'id': object_id\n",
    "        }\n",
    "\n",
    "    def add_property(self, name, value):\n",
    "        self._current_object[name] = value\n",
    "\n",
    "    def to_str(self):\n",
    "        return json.dumps(self._current_object)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "class XmlSerializer:\n",
    "    def __init__(self):\n",
    "        self._element = None\n",
    "\n",
    "    def start_object(self, object_name, object_id):\n",
    "        self._element = et.Element(object_name, attrib={'id': object_id})\n",
    "\n",
    "    def add_property(self, name, value):\n",
    "        prop = et.SubElement(self._element, name)\n",
    "        prop.text = value\n",
    "\n",
    "    def to_str(self):\n",
    "        return et.tostring(self._element, encoding='unicode')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [],
   "source": [
    "class YamlSerializer(JsonSerializer):\n",
    "    def to_str(self):\n",
    "        return yaml.dump(self._current_object)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [],
   "source": [
    "class SerializerFactory:\n",
    "\n",
    "    def __init__(self):\n",
    "        self._creators = {}\n",
    "\n",
    "    def register_format(self, format, creator):\n",
    "        self._creators[format] = creator\n",
    "\n",
    "    def get_serializer(self, format):\n",
    "        creator = self._creators.get(format)\n",
    "        if not creator:\n",
    "            raise ValueError(format)\n",
    "        return creator()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [],
   "source": [
    "factory = SerializerFactory()\n",
    "\n",
    "factory.register_format('JSON', JsonSerializer)\n",
    "factory.register_format('XML', XmlSerializer)\n",
    "factory.register_format('YAML', YamlSerializer)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [],
   "source": [
    "song = Song('1', 'Water of Love', 'Dire Straits')\n",
    "serializer = ObjectSerializer()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'{\"id\": \"1\", \"title\": \"Water of Love\", \"artist\": \"Dire Straits\"}'"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "serializer.serialize(song, 'JSON')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'<song id=\"1\"><title>Water of Love</title><artist>Dire Straits</artist></song>'"
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "serializer.serialize(song, 'XML')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\"{artist: Dire Straits, id: '1', title: Water of Love}\\n\""
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "serializer.serialize(song, 'YAML')"
   ]
  }
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object_factory_and_service_provider.ipynb

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