If a class attribute defines __get__ , accessing obj.attr becomes AttributeClass.__get__(attr, obj, type(obj)) .
class ValidatedAttribute: def __set_name__(self, owner, name): self.storage_name = f"_name" def __get__(self, obj, objtype=None): return getattr(obj, self.storage_name)
class HelloPlugin(Plugin): def run(self): print("Hello")
In Python, classes are themselves objects of a higher class called type . python 3 deep dive part 4 oop high quality
By implementing __len__ , your class becomes compatible with len() . Implement __getitem__ and __iter__ , and your objects become iterable. Override __add__ , __sub__ , and other arithmetic methods to give your classes mathematical behavior. Implement __enter__ and __exit__ to create context managers for the with statement.
class SingletonMeta(type): _instances = {} def __call__(cls, *args, **kwargs): if cls not in cls._instances: cls._instances[cls] = super().__call__(*args, **kwargs) return cls._instances[cls] class DatabaseConnection(metaclass=SingletonMeta): def __init__(self): self.connected = True Use code with caution. Factory Pattern Using Class Methods
for structural framework enforcement and global validation patterns. If a class attribute defines __get__ , accessing obj
By focusing on these deep concepts, you will move from writing Python code to designing elegant Python systems.
The request for a "paper" on refers to the advanced coursework by Fred Baptiste, which focuses on the internal mechanics of Object-Oriented Programming (OOP) in Python. Core Concepts Covered
: Learning about metaclasses and how they can be used to control the creation of classes themselves. Implement __getitem__ and __iter__ , and your objects
If classes define how objects behave, metaclasses define how classes behave. A class is itself an instance of a metaclass (by default, type ).
If an object implements __eq__ , it must also implement __hash__ to remain usable in sets and as dictionary keys. Mutability generally breaks hashability.
def process(self, data): if "id" not in data: raise ValueError("Missing ID") return data