class — Advanced Examples

Defines a new class (blueprint for creating objects)

EasyIntermediateAdvancedExpert

Multiple inheritance and MRO

Using multiple inheritance with method resolution order.

python
class Loggable:
    def log(self, message):
        print(f"[{self.__class__.__name__}] {message}")

class Serializable:
    def to_dict(self):
        return {k: v for k, v in self.__dict__.items()
                if not k.startswith("_")}

class User(Loggable, Serializable):
    def __init__(self, name, email):
        self.name = name
        self.email = email

u = User("Alice", "alice@example.com")
u.log("created")
print(u.to_dict())

# Method Resolution Order
print(User.__mro__)

Python uses C3 linearization for MRO. Multiple inheritance lets you compose behaviors from several base classes, but order matters.

Slots and memory optimization

Using __slots__ to restrict and optimize attribute storage.

python
import sys

class PointDict:
    def __init__(self, x, y):
        self.x = x
        self.y = y

class PointSlots:
    __slots__ = ("x", "y")
    def __init__(self, x, y):
        self.x = x
        self.y = y

pd = PointDict(1, 2)
ps = PointSlots(1, 2)

print(f"With __dict__: {sys.getsizeof(pd.__dict__)} bytes")
print(f"With __slots__: no __dict__")
print(f"ps.x = {ps.x}, ps.y = {ps.y}")

try:
    ps.z = 3
except AttributeError as e:
    print(f"Cannot add attribute: {e}")

__slots__ prevents __dict__ creation, saving ~40-60 bytes per instance. Useful when creating millions of objects.

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