OOPs in python

class_intro.ipynb

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   "cell_type": "markdown",
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   "source": [
    "# Class Defination\n",
    "A class is a blueprint of an object describing all the features of the object. Features imply that it can have some values and methods too as functionality."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [],
   "source": [
    "class item():\n",
    "    \"\"\"This is a class showing the shoping items\"\"\"\n",
    "    pass"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Creating a objects from a class using __\"()\"__"
   ]
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   "cell_type": "code",
   "execution_count": 4,
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   "outputs": [],
   "source": [
    "item01 = item()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Passing attributes by using __\".\"__ mehtod"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Phone 100 4\n"
     ]
    }
   ],
   "source": [
    "item01.name = \"Phone\"\n",
    "item01.price = 100\n",
    "item01.quantity = 4\n",
    "print(item01.name,item01.price,item01.quantity)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The above way of passing attributes to a variable is called as hard way to passing varibles"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "class item():\n",
    "    \"\"\"This is a class showing the shoping items\"\"\"\n",
    "    def __init__(self, name,price,quantity):\n",
    "        self.name=name\n",
    "        self.price=price\n",
    "        self.quantity = quantity\n",
    "    \n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "- In above code snippet the way of defining the `__init__`  method inside the class is to make the class more usable when instanciating objects from the class.\n",
    "- As it can be seen in above code snippet `self` keyword is used when passing the arguments to the `__init__` inside the class because it is used to pass the instance itself when creating a object from the class. "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Phone 100 4\n"
     ]
    }
   ],
   "source": [
    "item01 = item(\"Phone\", 100, 4)\n",
    "\n",
    "print(item01.name,item01.price,item01.quantity)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Definining methods inside the class"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [],
   "source": [
    "class item():\n",
    "    \"\"\"\n",
    "    This is a class showing the shoping items \n",
    "    takes attributes such as:\n",
    "    +++++++++++++++++++++++++++++++++++++++++++++++++\n",
    "    Name: Name of the Item \n",
    "    Price: Price of the Item \n",
    "    Quantity: Qauntity of the item \n",
    "    +++++++++++++++++++++++++++++++++++++++++++++++++\n",
    "    \"\"\"\n",
    "    def __init__(self, name,price,quantity):\n",
    "        self.name=name\n",
    "        self.price=price\n",
    "        self.quantity = quantity\n",
    "\n",
    "    def calculate_price(self):\n",
    "        return self.price*self.quantity"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
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     "text": [
      "400\n"
     ]
    }
   ],
   "source": [
    "item01 = item(\"Phone\", 100, 4)\n",
    "\n",
    "total_price=item01.calculate_price()\n",
    "\n",
    "print(total_price)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Asserting certain values in instanciating or else it should through error, using `assert` keyword."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [],
   "source": [
    "class item():\n",
    "    \n",
    "    \"\"\"\n",
    "    This is a class showing the shoping items \n",
    "    takes attributes such as:\n",
    "    +++++++++++++++++++++++++++++++++++++++++++++++++\n",
    "    Name: Name of the Item [Should be a string]\n",
    "    Price: Price of the Item [Should be greater than zero]\n",
    "    Quantity: Qauntity of the item [Should be grater than zero]\n",
    "    +++++++++++++++++++++++++++++++++++++++++++++++++\n",
    "    \"\"\"\n",
    "\n",
    "    def __init__(self, name,price,quantity):\n",
    "        assert price >=0, f\"Price {price} is not greater than or equal to zero! \"\n",
    "        assert quantity >= 0, f\"Qauntity {quantity} is not greater or equal to zero\"\n",
    "        assert type(name) == str, f\"Passed value as {name} should be string not {type(name)}\"\n",
    "\n",
    "        self.name=name\n",
    "        self.price=price\n",
    "        self.quantity = quantity\n",
    "\n",
    "    def calculate_price(self):\n",
    "        return self.price*self.quantity"
   ]
  },
  {
   "cell_type": "markdown",
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   "source": [
    "- Thus this will only take certain values values as mentioned in assert.\n",
    "- Thus passing anykind of different values may give error"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [],
   "source": [
    "item1 =  item(\"Phone\", 100,1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "ename": "AssertionError",
     "evalue": "Qauntity -3 is not greater or equal to zero",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mAssertionError\u001b[0m                            Traceback (most recent call last)",
      "\u001b[1;32m/mnt/c/Users/ashis/OneDrive/Documents/GitHub/Repositories/Python-Projects/BootCamp-Projects/class_intro.ipynb Cell 18'\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> <a href='vscode-notebook-cell://wsl%2Bubuntu-20.04/mnt/c/Users/ashis/OneDrive/Documents/GitHub/Repositories/Python-Projects/BootCamp-Projects/class_intro.ipynb#ch0000018vscode-remote?line=0'>1</a>\u001b[0m item2 \u001b[39m=\u001b[39m item(\u001b[39m\"\u001b[39;49m\u001b[39mLaptop\u001b[39;49m\u001b[39m\"\u001b[39;49m,\u001b[39m1000\u001b[39;49m,\u001b[39m-\u001b[39;49m\u001b[39m3\u001b[39;49m)\n",
      "\u001b[1;32m/mnt/c/Users/ashis/OneDrive/Documents/GitHub/Repositories/Python-Projects/BootCamp-Projects/class_intro.ipynb Cell 15'\u001b[0m in \u001b[0;36mitem.__init__\u001b[0;34m(self, name, price, quantity)\u001b[0m\n\u001b[1;32m     <a href='vscode-notebook-cell://wsl%2Bubuntu-20.04/mnt/c/Users/ashis/OneDrive/Documents/GitHub/Repositories/Python-Projects/BootCamp-Projects/class_intro.ipynb#ch0000014vscode-remote?line=12'>13</a>\u001b[0m \u001b[39mdef\u001b[39;00m \u001b[39m__init__\u001b[39m(\u001b[39mself\u001b[39m, name,price,quantity):\n\u001b[1;32m     <a href='vscode-notebook-cell://wsl%2Bubuntu-20.04/mnt/c/Users/ashis/OneDrive/Documents/GitHub/Repositories/Python-Projects/BootCamp-Projects/class_intro.ipynb#ch0000014vscode-remote?line=13'>14</a>\u001b[0m     \u001b[39massert\u001b[39;00m price \u001b[39m>\u001b[39m\u001b[39m=\u001b[39m\u001b[39m0\u001b[39m, \u001b[39mf\u001b[39m\u001b[39m\"\u001b[39m\u001b[39mPrice \u001b[39m\u001b[39m{\u001b[39;00mprice\u001b[39m}\u001b[39;00m\u001b[39m is not greater than or equal to zero! \u001b[39m\u001b[39m\"\u001b[39m\n\u001b[0;32m---> <a href='vscode-notebook-cell://wsl%2Bubuntu-20.04/mnt/c/Users/ashis/OneDrive/Documents/GitHub/Repositories/Python-Projects/BootCamp-Projects/class_intro.ipynb#ch0000014vscode-remote?line=14'>15</a>\u001b[0m     \u001b[39massert\u001b[39;00m quantity \u001b[39m>\u001b[39m\u001b[39m=\u001b[39m \u001b[39m0\u001b[39m, \u001b[39mf\u001b[39m\u001b[39m\"\u001b[39m\u001b[39mQauntity \u001b[39m\u001b[39m{\u001b[39;00mquantity\u001b[39m}\u001b[39;00m\u001b[39m is not greater or equal to zero\u001b[39m\u001b[39m\"\u001b[39m\n\u001b[1;32m     <a href='vscode-notebook-cell://wsl%2Bubuntu-20.04/mnt/c/Users/ashis/OneDrive/Documents/GitHub/Repositories/Python-Projects/BootCamp-Projects/class_intro.ipynb#ch0000014vscode-remote?line=15'>16</a>\u001b[0m     \u001b[39massert\u001b[39;00m \u001b[39mtype\u001b[39m(name) \u001b[39m==\u001b[39m \u001b[39mstr\u001b[39m, \u001b[39mf\u001b[39m\u001b[39m\"\u001b[39m\u001b[39mPassed value as \u001b[39m\u001b[39m{\u001b[39;00mname\u001b[39m}\u001b[39;00m\u001b[39m should be string not \u001b[39m\u001b[39m{\u001b[39;00m\u001b[39mtype\u001b[39m(name)\u001b[39m}\u001b[39;00m\u001b[39m\"\u001b[39m\n\u001b[1;32m     <a href='vscode-notebook-cell://wsl%2Bubuntu-20.04/mnt/c/Users/ashis/OneDrive/Documents/GitHub/Repositories/Python-Projects/BootCamp-Projects/class_intro.ipynb#ch0000014vscode-remote?line=17'>18</a>\u001b[0m     \u001b[39mself\u001b[39m\u001b[39m.\u001b[39mname\u001b[39m=\u001b[39mname\n",
      "\u001b[0;31mAssertionError\u001b[0m: Qauntity -3 is not greater or equal to zero"
     ]
    }
   ],
   "source": [
    "item2 = item(\"Laptop\",1000,-3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Here in above as you can see that it is showing such error because we have provided error message in the assertion error"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "    This is a class showing the shoping items \n",
      "    takes attributes such as:\n",
      "    +++++++++++++++++++++++++++++++++++++++++++++++++\n",
      "    Name: Name of the Item [Should be a string]\n",
      "    Price: Price of the Item [Should be greater than zero]\n",
      "    Quantity: Qauntity of the item [Should be grater than zero]\n",
      "    +++++++++++++++++++++++++++++++++++++++++++++++++\n",
      "    \n"
     ]
    }
   ],
   "source": [
    "print(item.__doc__)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Here in above the `__doc__` is used to see what this class doc string is "
   ]
  }
 ],
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