Checking class equality

In the previous exercise, you defined a BankAccount class with a number attribute that was used for comparison. But if you were to compare a BankAccount object to an object of another class that also has a number attribute, you could end up with unexpected results.

For example, consider two classes


class Phone:
    def __init__(self, number):
        self.number = number

    def __eq__(self, other):
        return self.number == \
               other.number

pn = Phone(873555333)


class BankAccount:
    def __init__(self, number):
        self.number = number

    def __eq__(self, other):
        return self.number == \
               other.number

acct = BankAccount(873555333)

Running acct == pn will return True, even though it compares a phone number with a bank account number.

It is good practice to check the class of objects passed to the __eq__() method to make sure the comparison makes sense.

This exercise is part of the course

Introduction to Object-Oriented Programming in Python

View Course

Exercise instructions

Modify the definition of BankAccount to only return True if the number attribute is the same and the type() of both objects passed to it is the same.
Check if acct and pn are equal.

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

class BankAccount:
  def __init__(self, number, balance=0):
    self.number, self.balance = number, balance
      
  def withdraw(self, amount):
    self.balance -= amount 

  # Modify to add a check for the class type
  def __eq__(self, other):
    return (self.number == other.number) ____

acct = BankAccount(873555333)
pn = Phone(873555333)

# Check if the two objects are equal
print(____)

Edit and Run Code