What is the purpose of the __slots__ keyword in Python?

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Answer:

The __slots__ keyword in Python is used to define a fixed set of attributes for a class. When a class defines __slots__, it restricts the creation of instance variables to only those defined in the __slots__ declaration.

The primary purpose of __slots__ is to reduce memory usage and improve performance in situations where many instances of a class need to be created. By restricting the set of possible instance variables, Python can allocate memory more efficiently and avoid the memory overhead of a dictionary that would be used for dynamic attribute storage.

Here's an example to illustrate the use of __slots__:

class Person:
    __slots__ = ['name', 'age']
    
    def __init__(self, name, age):
        self.name = name
        self.age = age

In this example, the Person class defines __slots__ to include the name and age attributes. This means that instances of the Person class can only have those two attributes, and any attempts to add new attributes will result in an AttributeError.

Using __slots__ can offer significant memory savings, especially for classes that create many instances or that have many small attributes. However, it's important to note that __slots__ also has some limitations, such as preventing the use of dynamic attributes and making it harder to subclass the class. Therefore, it's important to use __slots__ judiciously and only when you have a good reason to do so.

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