3. Operations declaration and inheritance¶

Add the method statement to the Account class that prints a list of deposit and withdrawal operations.
Change the __init__ method to use the deposit method to initialize the balance.

3.1. Client Class and Improved Account Class¶

 
class Client:
    def __init__(self, name, phone):
        self.name = name
        self.phone = phone
​
​
class Account:
    def __init__(self, clients, number, balance=0):
        self.balance = 0
        self.clients = clients
        self.number = number
        self.operations = []
        self.deposit(balance)
​
    def summary(self):
        print("Account number: %s \nBalance: %10.2f" % (self.number, self.balance))
​
    def withdraw(self, amount):
        if self.balance >= amount:
            self.balance -= amount
            self.operations.append(["Withdrawal", amount])
        else:
            print("Not enough funds for withdrawal")
​

Activity: 3.1.1 ActiveCode (ac_l25_3a_en)

3.1.1. Using the Client and Improved Account Classes¶

 
juan = Client("Juan de Silva", "777-1234")
maria = Client("Maria de Silva", "555-4321")
account_1 = Account([juan], 1, 1000)
account_2 = Account([maria, juan], 2, 500)
​
account_1.withdraw(50)
account_2.deposit(300)
account_1.withdraw(190)
account_2.deposit(95.15)
account_2.withdraw(250)
​
account_1.statement()
account_2.statement()
​

Activity: 3.1.1.1 ActiveCode (ac_l25_3b_en)

3.2. Inheritance¶

Object inheritance allows us to modify our classes by adding or modifying attributes and methods based on the previous class.
We will create special accounts where we can withdraw more money than the balance, up to a certain limit.
Deposit, withdrawal, and summary operations continue as a regular account.

3.3. Special Account Class¶

 
class SpecialAccount(Account):
    def __init__(self, clients, number, balance=0, limit=0):
        Account.__init__(self, clients, number, balance)
        self.limit = limit
​
    def withdraw(self, amount):
        if self.balance + self.limit >= amount:
            self.balance -= amount
            self.operations.append(["Withdrawal", amount])
        else:
            print("Not enough funds for withdrawal")
​

Activity: 3.3.1 ActiveCode (ac_l25_3c_en)

Note that we wrote Account in parentheses.
SpecialAccount inherits the methods and attributes of Account.
self.limit will only be created for classes of type SpecialAccount.
Note that we are completely overriding the withdraw method in SpecialAccount.

3.4. Advantages of Inheritance¶

We have made minimal changes to our program, maintaining previous functionality and adding new features.
It was possible to reuse account methods.
Therefore, the definition of the SpecialAccount class was much simpler, including only the different behavior.

3.5. Using all classes¶

 
juan = Client("Juan de Silva", "777-1234")
maria = Client("Maria de Silva", "555-4321")
account_1 = Account([juan], 1, 1000)
account_2 = SpecialAccount([maria, juan], 2, 500, 1000)
​
account_1.withdraw(50)
account_2.deposit(300)
account_1.withdraw(190)
account_2.deposit(95.15)
account_2.withdraw(1500)
​
account_1.statement()
account_2.statement()
​

Activity: 3.5.1 ActiveCode (ac_l25_3d_en)

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