Creating descriptors

A descriptor is a class that mediates attribute access. The descriptor class can be used to get, set, or delete attribute values. Descriptor objects are built inside a class at class definition time. Descriptors are the essence of how Python implements methods, attributes, and properties.

The descriptor design pattern has two parts: an owner class and the attribute descriptor itself. The owner class uses one or more descriptors for its attributes. A descriptor class defines some combination of the __get__, __set__, and __delete__ methods. An instance of the descriptor class will be an attribute of the owner class.

A descriptor is an instance of a class that is separate from the owning class. Therefore, descriptors let ...

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