What is the difference between a class attribute and an instance attribute in Python?Gable E
In Python, class attributes and instance attributes are both ways to store and access data associated with a class. However, they have distinct behaviors and purposes. Here's a long-form explanation of the differences between class attributes and instance attributes: Class Attributes: 1. Definition: - Class attributes are variables defined within a class but outside of any methods. - They are shared among all instances of the class and belong to the class itself. - Class attributes are defined directly in the class body, typically at the top, and are accessed using the class name or any instance of the class. 2. Access and Modification: - Class attributes can be accessed and modified by any instance of the class or by the class itself. - When accessing a class attribute, Python first checks if the attribute exists in the instance. If not found, it looks for the attribute in the class. - Modifying a class attribute affects all instances of the class, as they share the same attribute value. 3. Example:
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class MyClass: class_attribute = "Class Value" instance1 = MyClass() instance2 = MyClass() print(instance1.class_attribute) # Output: Class Value print(instance2.class_attribute) # Output: Class Value MyClass.class_attribute = "New Value" print(instance1.class_attribute) # Output: New Value print(instance2.class_attribute) # Output: New Value
- Instance attributes are variables specific to each instance of a class.
- They are defined and accessed within methods or the
__init__ method (constructor) of the class.
- Each instance of the class has its own set of instance attributes, which are separate from other instances.
2. Access and Modification: