Oop

Accessing r.width and writing r.width = 15 with the same syntax as a plain attribute, while running validation or computation under the hood: that is what @property provides. And when that logic needs to be shared across multiple classes, descriptors come into play. @property: getters and setters without friction @property lets you expose a computed or validated attribute with the same syntax as a regular one. class Rectangle: def __init__(self, width: float, height: float): self._width = width self._height = height @property def width(self) -> float: return self._width @width.setter def width(self, value: float) -> None: if value <= 0: raise ValueError("Width must be positive.") self._width = value @property def area(self) -> float: return self._width * self._height The concrete benefit: the public API does not change. Adding validation to an existing attribute breaks no calling code. @property without a setter creates a read-only attribute. @name.deleter handles deletion via del. ...