Using Python's .__dict__ to Work with Attributes – Real Python

Using Python's .dict to Work with Attributes – Real Python

a year ago

Python's .__dict__ is a special attribute in classes and instances that maps attribute names to their values.
.__dict__ allows dynamic inspection, modification, addition, or deletion of attributes, making it useful for metaprogramming and debugging.
Both vars() and .__dict__ can inspect an object's attributes, with .__dict__ providing direct access to the object's namespace.
Common use cases for .__dict__ include dynamic attribute management, introspection, serialization, and debugging.
.__dict__ is fundamental to Python's data model and is used internally by the interpreter for dynamic attribute access.
Classes and instances have separate .__dict__ attributes, with instance .__dict__ containing only instance-specific attributes.
Functions also have a .__dict__ attribute, which can be used to attach metadata or for caching purposes.
Built-in functions and data types may not have a .__dict__ attribute, as they are implemented in C for efficiency.
.__dict__ can be used for memoization, serializing objects to JSON, and customizing attribute access with special methods like __getattribute__ and __setattr__.
Descriptors can use .__dict__ to avoid recursion issues when implementing __get__ and __set__ methods.