Object_Oriented_Python_4_Instances_advanced.ipynb

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   "source": [
    "# Part 4 - Instances: advanced topics"
   ]
  },
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Method resolution"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "class Lift:\n",
    "    max_weight = 100\n",
    "    \n",
    "    def __init__(self, f, s):\n",
    "        self.floor = f\n",
    "        self.status = s\n",
    "    \n",
    "    def open(self):\n",
    "        self.status = 'open'\n",
    "\n",
    "    def close(self):\n",
    "        self.status = 'closed'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "lift = Lift(1, \"open\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "Lift.__dict__"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "lift.__dict__"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Attributes are resolved at runtime"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "lift.max_weight is Lift.max_weight"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Are methods resolved the same way?"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "lift.open is Lift.open"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "Lift.__dict__['open']"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "Lift.open"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "lift.open"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Override attribute resolution"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "class Lift:\n",
    "    def __init__(self, f, s):\n",
    "        self.floor = f\n",
    "        self.status = s\n",
    "        \n",
    "    def open(self):\n",
    "        self.status = 'open'\n",
    "        \n",
    "    def close(self):\n",
    "        self.status = 'closed'\n",
    "        \n",
    "    def __getattr__(self, attr):\n",
    "        if attr == 'colour':\n",
    "            return 'red'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "lift = Lift(1, \"closed\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "lift.floor"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "lift.status"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "lift.colour"
   ]
  }
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