: An in-depth look at class data and function attributes, emphasizing that classes themselves are callables and objects in Python.
A bound method automatically injects the instance ( p ) as the first argument ( self ) into the underlying function. Class Methods and Static Methods
: Implement only __get__ (e.g., standard methods). Instance dictionaries take precedence over them.
When the same property logic needs to be shared across completely different classes and attributes, properties become repetitive. This is where come in. A descriptor is any object that defines at least one of the following dunder methods: __get__ , __set__ , or __delete__ . Here is how you can build a reusable validator descriptor:
class BankAccount: def __init__(self, owner, balance): self.owner = owner self._balance = balance # Protected naming convention @property def balance(self): return self._balance @balance.setter def balance(self, value): if value < 0: raise ValueError("Balance cannot be negative.") self._balance = value Use code with caution. The Descriptor Protocol python 3 deep dive part 4 oop
class BankAccount: def __init__(self, balance): self._balance = balance @property def balance(self): return self._balance @balance.setter def balance(self, value): if value < 0: raise ValueError("Balance cannot be negative") self._balance = value Use code with caution. 5. Inheritance and Polymorphism
class EnforceCapsMeta(type): def __new__(mcs, name, bases, class_dict): # Modify class attributes before creation upper_dict = {} for key, val in class_dict.items(): if not key.startswith('__'): upper_dict[key.upper()] = val else: upper_dict[key] = val return super().__new__(mcs, name, bases, upper_dict) class Content(metaclass=EnforceCapsMeta): title = "Advanced Python" # Verification obj = Content() print(hasattr(obj, 'title')) # Output: False print(hasattr(obj, 'TITLE')) # Output: True Use code with caution.
By default, Python uses the type metaclass to construct classes. However, you can write custom metaclasses to intercept, modify, validate, or register classes at the exact moment they are defined by the compiler. Creating a Custom Metaclass
class Wheels: def rotate(self): pass
This report assumes you have a basic understanding of Python classes but want to explore the deeper mechanics, advanced patterns, and internals of Python’s OOP model.
correctly, ensuring that method calls propagate through the inheritance chain without repetition or omission. Metaclasses: The Ultimate Abstraction The climax of Python OOP is Metaclasses
class LazyRecord: def __init__(self): self.exists = 1 def __getattr__(self, name): print(f"Computing name on demand") return f"Generated name"
class Book: def __init__(self, title, author, year): self.title = title self.author = author self.year = year self.checked_out = False : An in-depth look at class data and
def __repr__(self): return f"Vector(self.x, self.y)"
: With over 36 hours of video content , the course moves far beyond basic class syntax into complex internals like metaprogramming and the descriptor protocol .
Mastering OOP in Python 3, as taught in deep-dive courses, requires moving beyond basic syntax to understand how objects, classes, and inheritance interact with Python's dynamic nature. By utilizing __dict__ , properties, super() , and dunder methods effectively, developers can write more robust and maintainable code.
my_dog.bark() # Output: Woof! my_dog.wag_tail() # Output: Wagging my tail! Instance dictionaries take precedence over them