CODEWITHSUNDEEP
pythonclassoopinheritancesuper
Milind Sharma
Milind Sharma

Reputation: 322

How to initialise an inherited class in Python

I'm having a hard time understanding how to initialize an inherited class in python OOP.

I cannot figure out what arguments need to be passed when I initialize it. These are the classes I'm using:

class BankAccount:  #parent class

    def __init__(self, owner, balance):
        self.owner = owner
        self.balance = balance

    def withdrawal(self, withdraw):
        if withdraw > self.balance:
            raise RuntimeError('Sorry, Insufficient Funds!')
        else:
            print('Withdrawal accepted.')
            self.balance -= withdraw
            show_balance = input('See account balance? enter y or n: ')
            if show_balance == 'y':
                print(self.balance)

    def deposit(self, amt):
        self.balance += amt
        print('Deposit Accepted')
        show_balance = input('See account balance? enter y or n: ')
        if show_balance == 'y':
            print(self.balance)


class MinimumBalanceAccount(BankAccount):        #child class

    minimum_balance = 100

    def __init__(self):
        BankAccount.__init__(self)

    def withdrawal(self, withdraw):
        if self.balance - withdraw < self.minimum_balance:
            print('Error, balance cannot go below minimum value: {}'.format(minimum_balance))
        else:
            self.balance -= withdraw

But when I try to initialize the child class:

acc2 = MinimumBalanceAccount('Milind', 1000)    # I am not sure what to pass as arguments here

Python gives me this error:

TypeError                                 Traceback (most recent call last)
<ipython-input-9-85e55fb15340> in <module>
----> 1 acc2 = MinimumBalanceAccount('milind', 1000)

TypeError: __init__() takes 1 positional argument but 3 were given

What do I pass in as the arguments?? What's going wrong?

Upvotes: 1

Views: 366

Answers (3)

Trilok Venkat
Trilok Venkat

Reputation: 46

class MinimumBalanceAccount(BankAccount): #child class

minimum_balance = 100

def __init__(self,owner, balance):
    BankAccount.__init__(self,owner,balance)

def withdrawal(self, withdraw):
    if self.balance - withdraw < self.minimum_balance:
        print('Error, balance cannot go below minimum value: {}'.format(minimum_balance))
    else:
        self.balance -= withdraw

Upvotes: 0

Reblochon Masque
Reblochon Masque

Reputation: 36732

You need to pass the required arguments to the subclass, and to the superclass:

class BankAccount:

    def __init__(self, owner, balance):
        self.owner = owner
        self.balance = balance

    def withdrawal(self, withdraw):
        if withdraw > self.balance:
            raise RuntimeError('Sorry, Insufficient Funds!')
        else:
            print('Withdrawal accepted.')
            self.balance -= withdraw
            show_balance = input('See account balance? enter y or n: ')
            if show_balance == 'y':
                print(self.balance)

    def deposit(self, amt):
        self.balance += amt
        print('Deposit Accepted')
        show_balance = input('See account balance? enter y or n: ')
        if show_balance == 'y':
            print(self.balance)


class MinimumBalanceAccount(BankAccount):

    minimum_balance = 100

    def __init__(self, owner, balance):
        super().__init__(owner, balance)
        self.minimum_balance = MinimumBalanceAccount.minimum_balance

    def withdrawal(self, withdraw):
        if self.balance - withdraw < self.minimum_balance:
            print('Error, balance cannot go below minimum value: {}'.format(minimum_balance))
        else:
            self.balance -= withdraw

acc2 = MinimumBalanceAccount('Milind', 1000)

In this case, as pointed out by @Deceze in the comments, you can omit __init__ entirely:

class MinimumBalanceAccount(BankAccount):        #child class

    minimum_balance = 100

    def withdrawal(self, withdraw):
        if self.balance - withdraw < self.minimum_balance:
            print('Error, balance cannot go below minimum value: {}'.format(minimum_balance))
        else:
            self.balance -= withdraw

Upvotes: 2

sebastian-ruehmann
sebastian-ruehmann

Reputation: 503

You need to add the initializing parameters also to your child Class when you define the __init__ function and pass it to the parent.

class MinimumBalanceAccount(BankAccount):        #child class

    minimum_balance = 100

    def __init__(self, owner, balance):
        BankAccount.__init__(self, owner, balance)

Upvotes: 1

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