Python
Advanced
What is Python Descriptors?
Objects that define __get__, __set__, or __delete__ methods, controlling how attribute access works on other objects.
Descriptors are the mechanism behind properties, class methods, static methods, and slots in Python. When an object defines __get__(), __set__(), or __delete__(), it becomes a descriptor. Data descriptors (with __set__ or __delete__) take precedence over instance dictionaries, while non-data descriptors (only __get__) defer to instance attributes. This protocol powers Django ORM fields, SQLAlchemy columns, and validation frameworks. Understanding descriptors reveals how Python's attribute access truly works — when you access obj.attr, Python calls type(obj).__dict__['attr'].__get__(obj, type(obj)) if attr is a descriptor.
