python-kurs-softed/notebooks/objects.ipynb

{
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   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Objekte und OO-Programmierung"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "```py\n",
    "# Ausgangslage\n",
    "employees = {\n",
    "    \"name 1\": {\n",
    "        \"salary\": ...,\n",
    "        \"skills\": [...],\n",
    "    },\n",
    "    \"name 2\": {\n",
    "        \"salary\": ...,\n",
    "        \"skills\": [...],\n",
    "    },\n",
    "    ...\n",
    "}\n",
    "```"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Unknown\n",
      "0\n",
      "[]\n",
      "Unknown\n",
      "0\n",
      "[]\n"
     ]
    }
   ],
   "source": [
    "class Employee:\n",
    "    name = \"Unknown\"\n",
    "    gehalt = 0\n",
    "    skills = []\n",
    "\n",
    "employee1 = Employee()\n",
    "print(employee1.name)\n",
    "print(employee1.gehalt)\n",
    "print(employee1.skills)\n",
    "\n",
    "employee2 = Employee()\n",
    "print(employee2.name)\n",
    "print(employee2.gehalt)\n",
    "print(employee2.skills)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Joe Doe\n",
      "Unknown\n"
     ]
    }
   ],
   "source": [
    "employee1.name = \"Joe Doe\"\n",
    "print(employee1.name)\n",
    "print(employee2.name)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Init!\n"
     ]
    }
   ],
   "source": [
    "class Employee:\n",
    "    def __init__(self):\n",
    "        print(\"Init!\")\n",
    "    \n",
    "employee3 = Employee()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "<class '__main__.Employee'>\n",
      "Joe Doe\n",
      "2000\n",
      "[]\n",
      "Jane Oh\n",
      "3000\n",
      "['marketing']\n"
     ]
    }
   ],
   "source": [
    "class Employee:\n",
    "    def __init__(self, name=\"\", gehalt=0, skills=[]):\n",
    "        self.name = name\n",
    "        self.gehalt = gehalt\n",
    "\n",
    "        if skills is None:\n",
    "            self.skills = []\n",
    "        else:\n",
    "            self.skills = skills\n",
    "\n",
    "employee4 = Employee(\"Joe Doe\", 2000, [])\n",
    "print(type(employee4))\n",
    "print(employee4.name)\n",
    "print(employee4.gehalt)\n",
    "print(employee4.skills)#\n",
    "\n",
    "employee5 = Employee(\"Jane Oh\", 3000, [\"marketing\"])\n",
    "print(employee5.name)\n",
    "print(employee5.gehalt)\n",
    "print(employee5.skills)\n",
    "\n",
    "# Geht nicht, weil die Klasse kein Attribut \"name\" definiert\n",
    "#print(Employee.name)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "0\n",
      "[]\n"
     ]
    }
   ],
   "source": [
    "employee6 = Employee()\n",
    "print(employee6.name)\n",
    "print(employee6.gehalt)\n",
    "print(employee6.skills)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Employee 'Bob Smith'\n",
      "    gehalt: 0\n",
      "    skills:\n",
      "        - software development\n",
      "        - it support\n"
     ]
    }
   ],
   "source": [
    "class Employee:\n",
    "    def __init__(self, name=\"\", gehalt=0, skills=[]):\n",
    "        self.name = name\n",
    "        self.gehalt = gehalt\n",
    "\n",
    "        if skills is None:\n",
    "            self.skills = []\n",
    "        else:\n",
    "            self.skills = skills\n",
    "\n",
    "    def __str__(self):\n",
    "        s  = [f\"Employee '{self.name}'\"]\n",
    "        s.append(f\"    gehalt: {self.gehalt}\")\n",
    "        s.append(f\"    skills:\")\n",
    "        for skill in self.skills:\n",
    "            s.append(f\"        - {skill}\")\n",
    "        return \"\\n\".join(s)\n",
    "\n",
    "\"\"\"\n",
    "Employee 'name':\n",
    "    gehalt: XXX\n",
    "    skills:\n",
    "        - skill 1\n",
    "        - skill 2\n",
    "\"\"\"\n",
    "employee7 = Employee(name=\"Bob Smith\", skills=[\"software development\", \"it support\"])\n",
    "print(employee7)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Hallo, Welt\n",
      "Guten Tag, Welt\n",
      "Welt, Guten Tag\n",
      "Welt, Guten Tag\n",
      "Guten Tag, Welt\n"
     ]
    }
   ],
   "source": [
    "# Exkurs: Strings und `format()`\n",
    "\n",
    "s = \"Hallo, {}\"\n",
    "print(s.format(\"Welt\"))\n",
    "\n",
    "s = \"{}, {}\"\n",
    "print(s.format(\"Guten Tag\", \"Welt\"))\n",
    "\n",
    "s = \"{name}, {grussformel}\"\n",
    "print(s.format(grussformel=\"Guten Tag\", name=\"Welt\"))\n",
    "\n",
    "grussformel=\"Guten Tag\"\n",
    "name=\"Welt\"\n",
    "print(f\"{name}, {grussformel}\")\n",
    "\n",
    "\n",
    "def sagehallo(name):\n",
    "    # 'grussformel' ist eine globale variable!\n",
    "    print(f\"{grussformel}, {name}\")\n",
    "\n",
    "sagehallo(\"Welt\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "5000\n"
     ]
    },
    {
     "ename": "ValueError",
     "evalue": "Zu hohes gehalt!",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mValueError\u001b[0m                                Traceback (most recent call last)",
      "\u001b[1;32m/home/chris/work/python-kurs-softed/notebooks/objects.ipynb Cell 10\u001b[0m line \u001b[0;36m2\n\u001b[1;32m     <a href='vscode-notebook-cell:/home/chris/work/python-kurs-softed/notebooks/objects.ipynb#X12sZmlsZQ%3D%3D?line=21'>22</a>\u001b[0m \u001b[39mprint\u001b[39m(employee8\u001b[39m.\u001b[39mgehalt)\n\u001b[1;32m     <a href='vscode-notebook-cell:/home/chris/work/python-kurs-softed/notebooks/objects.ipynb#X12sZmlsZQ%3D%3D?line=22'>23</a>\u001b[0m \u001b[39m# ValueError!\u001b[39;00m\n\u001b[0;32m---> <a href='vscode-notebook-cell:/home/chris/work/python-kurs-softed/notebooks/objects.ipynb#X12sZmlsZQ%3D%3D?line=23'>24</a>\u001b[0m employee8\u001b[39m.\u001b[39;49mset_gehalt(\u001b[39m4000\u001b[39;49m)\n\u001b[1;32m     <a href='vscode-notebook-cell:/home/chris/work/python-kurs-softed/notebooks/objects.ipynb#X12sZmlsZQ%3D%3D?line=24'>25</a>\u001b[0m \u001b[39m# TypeError!\u001b[39;00m\n\u001b[1;32m     <a href='vscode-notebook-cell:/home/chris/work/python-kurs-softed/notebooks/objects.ipynb#X12sZmlsZQ%3D%3D?line=25'>26</a>\u001b[0m employee8\u001b[39m.\u001b[39mset_gehalt(\u001b[39m\"\u001b[39m\u001b[39mein sack mehl\u001b[39m\u001b[39m\"\u001b[39m)\n",
      "\u001b[1;32m/home/chris/work/python-kurs-softed/notebooks/objects.ipynb Cell 10\u001b[0m line \u001b[0;36m1\n\u001b[1;32m     <a href='vscode-notebook-cell:/home/chris/work/python-kurs-softed/notebooks/objects.ipynb#X12sZmlsZQ%3D%3D?line=14'>15</a>\u001b[0m     \u001b[39mself\u001b[39m\u001b[39m.\u001b[39mgehalt \u001b[39m=\u001b[39m neues_gehalt\n\u001b[1;32m     <a href='vscode-notebook-cell:/home/chris/work/python-kurs-softed/notebooks/objects.ipynb#X12sZmlsZQ%3D%3D?line=15'>16</a>\u001b[0m \u001b[39melse\u001b[39;00m:\n\u001b[0;32m---> <a href='vscode-notebook-cell:/home/chris/work/python-kurs-softed/notebooks/objects.ipynb#X12sZmlsZQ%3D%3D?line=16'>17</a>\u001b[0m     \u001b[39mraise\u001b[39;00m \u001b[39mValueError\u001b[39;00m(\u001b[39m\"\u001b[39m\u001b[39mZu hohes gehalt!\u001b[39m\u001b[39m\"\u001b[39m)\n",
      "\u001b[0;31mValueError\u001b[0m: Zu hohes gehalt!"
     ]
    }
   ],
   "source": [
    "class Employee:\n",
    "    def __init__(self, name=\"\", gehalt=0, skills=[]):\n",
    "        self.name = name\n",
    "        self.gehalt = gehalt\n",
    "\n",
    "        if skills is None:\n",
    "            self.skills = []\n",
    "        else:\n",
    "            self.skills = skills\n",
    "\n",
    "    def set_gehalt(self, neues_gehalt):\n",
    "        if not isinstance(neues_gehalt, int):\n",
    "            raise TypeError(\"gehalt muss ein Integer sein\")\n",
    "        if neues_gehalt < 4000:\n",
    "            self.gehalt = neues_gehalt\n",
    "        else:\n",
    "            raise ValueError(\"Zu hohes gehalt!\")\n",
    "\n",
    "employee8 = Employee()\n",
    "# Ok\n",
    "employee8.gehalt = 5000\n",
    "print(employee8.gehalt)\n",
    "# ValueError!\n",
    "employee8.set_gehalt(4000)\n",
    "# TypeError!\n",
    "employee8.set_gehalt(\"ein sack mehl\")\n"
   ]
  }
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