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5.1 Classes and Objects

Python classes bundle data and behavior with minimal syntax overhead.

Basic class pattern​

class BankAccount:
    def __init__(self, owner, balance=0):
        self.owner = owner
        self.balance = balance

    def deposit(self, amount):
        self.balance += amount

Important OOP semantics​

  • Instance methods receive the instance as first parameter (conventionally self).
  • Class attributes are shared; instance attributes are per-object.
  • Attribute lookup checks instance first, then class, then base classes.

Inheritance and super()​

class SavingsAccount(BankAccount):
    def __init__(self, owner, balance=0, rate=0.03):
        super().__init__(owner, balance)
        self.rate = rate

Python uses method resolution order (MRO), especially relevant with multiple inheritance.

Iterators and generators in class design​

  • Iteration uses iter(obj) and next(iterator) protocols.
  • Generator methods can yield values lazily and simplify iteration logic.

Official references​