Python 3 Deep Dive Part 4 Oop Now

In Python, everything is an object – integers, strings, functions, classes, and even types themselves. Each object has:

A specific, concrete instance of a class.

instructor = Speaker() print(type(instructor.say_hello)) # Output: Use code with caution. The Magic Behind self Injection python 3 deep dive part 4 oop

def __add__(self, other): return Vector(self.x + other.x, self.y + other.y)

In Python, classes are objects; they are instances of a . The default metaclass is type , but you can create your own to intercept the creation of a class. In Python, everything is an object – integers,

class A: def action(self): print("A") class B(A): def action(self): print("B"); super().action() class C(A): def action(self): print("C"); super().action() class D(B, C): def action(self): print("D"); super().action() Use code with caution. Calling D().action() produces the output: D -> B -> C -> A . Rules of super() super() does not simply point to the parent class.

Properties allow you to define getter, setter, and deleter methods that expose an interface looking exactly like a standard attribute. The Magic Behind self Injection def __add__(self, other):

class Order: quantity = PositiveNumber() price = PositiveNumber()

class Engine: pass print(type(Engine)) # Output: print(isinstance(Engine, type)) # Output: True Use code with caution.

By default, Python instances store attributes in a per-object dictionary ( __dict__ ). While this provides exceptional flexibility (you can add attributes at runtime), it comes with a memory cost. Each dictionary has its own memory overhead, which can be significant when you create millions of small objects.

d = D() d.process() # Output: # D process # B process # C process # Note: A.process() is NOT called here because C did not call super(). # If C called super(), A would run.