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    "### <center>San Jose State University<br>Department of Applied Data Science<br><br>**DATA 200<br>Computational Programming for Data Analytics**<br><br>Spring 2024<br>Instructor: Ron Mak</center>"
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    "## 10.2.2 `Account` Class Definition\n",
    "#### Recall our import:\n",
    "``` Python\n",
    "from account import Account\n",
    "```\n",
    "#### Therefore, we define our custom class `Account` in Python source file `account.py`:\n",
    "``` Python\n",
    "from decimal import Decimal\n",
    "\n",
    "class Account:\n",
    "    \"\"\"\n",
    "    Account class for maintaining a bank account balance.\n",
    "    \"\"\"\n",
    "    def __init__(self, name, balance):\n",
    "        \"\"\"\n",
    "        Constructor of an Account object.\n",
    "        @param name the account holder's name.\n",
    "        @param balance the initial account balance.\n",
    "        \"\"\"\n",
    "        # If the balance is less than 0.00, raise an exception\n",
    "        if balance < Decimal('0.00'):\n",
    "            raise ValueError('Initial balance must be >= to 0.00.')\n",
    "\n",
    "        self.name = name\n",
    "        self.balance = balance\n",
    "\n",
    "    def deposit(self, amount):\n",
    "        \"\"\"\n",
    "        Deposit money to the account.\n",
    "        @param amount the amount to deposit.\n",
    "        \"\"\"\n",
    "        # if amount is less than 0.00, raise an exception\n",
    "        if amount < Decimal('0.00'):\n",
    "            raise ValueError('amount must be positive.')\n",
    "\n",
    "        self.balance += amount\n",
    "        \n",
    "    def display(self):\n",
    "        \"\"\"\n",
    "        Display the balance.\n",
    "        \"\"\"\n",
    "        print(f'Account for {self.name} has ${self.balance:.2f}')\n",
    "```"
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    "#### Note that `account.py` itself imports class `Decimal` from the `decimal` module. This is an example of **class composition** -- class `Account` is composed of another class, `Decimal`. Computer scientists call this a ***has-a*** relationship --  `Account` has a `Decimal`."
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    "#### Recall that **methods** are functions associated with objects. The methods are defined in the class definition."
   ]
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    "#### Class `Account` defines a special **constructor** method `__init__()` which is automatically called during run time whenever we instantiate (construct) an object of the class:\n",
    "``` Python\n",
    "account1 = Account('John Green', Decimal('50.00'))\n",
    "```\n",
    "#### The constructor for `Account` initializes the `name` and `balance` **attributes** of the object being constructed. Note that the constructor for a class is always named `__init__` with *double underscores* at the beginning and at the end."
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    "from account import Account\n",
    "from decimal import Decimal\n",
    "\n",
    "account1 = Account('John Green', Decimal('50.00'))\n",
    "account1.display()"
   ]
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   "source": [
    "#### Class `Account` defines two methods for its objects, `deposit()` and `withdraw()`. They look like regular function definitions, but they're defined inside the class definition."
   ]
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    "#### Whenever we call a method on an object, such as\n",
    "``` Python\n",
    "account1.deposit(Decimal('25.53'))`\n",
    "```\n",
    "#### Pythom *implicitly* passes the object as the first argument to the method. That's why every method definition, including the constructor, has `self` as its first parameter. In each method's code, `self` refers to the object that the method was called on. For example, when we call the `deposit()` method in an `Account` object, `self.balance += amount` adds the value of `amount` to the value of that object's `balance` attribute."
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    "account1.deposit(Decimal('25.53'))\n",
    "account1.display()"
   ]
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   "source": [
    "##########################################################################\n",
    "# (C) Copyright 2019 by Deitel & Associates, Inc. and                    #\n",
    "# Pearson Education, Inc. All Rights Reserved.                           #\n",
    "#                                                                        #\n",
    "# DISCLAIMER: The authors and publisher of this book have used their     #\n",
    "# best efforts in preparing the book. These efforts include the          #\n",
    "# development, research, and testing of the theories and programs        #\n",
    "# to determine their effectiveness. The authors and publisher make       #\n",
    "# no warranty of any kind, expressed or implied, with regard to these    #\n",
    "# programs or to the documentation contained in these books. The authors #\n",
    "# and publisher shall not be liable in any event for incidental or       #\n",
    "# consequential damages in connection with, or arising out of, the       #\n",
    "# furnishing, performance, or use of these programs.                     #\n",
    "##########################################################################\n"
   ]
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   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "# Additional material (C) Copyright 2024 by Ronald Mak"
   ]
  }
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