Why is __init__() Always Called After __new__() in Python?

Understanding the Relationship Between __new__() and __init__()

The __new__() and __init__() methods in Python play crucial roles in the creation and initialization of class instances. __new__() is invoked before __init__() and is responsible for constructing a new class instance by allocating memory for it. On the other hand, __init__() is employed to initialize the instance's attributes and perform any necessary setup.

Now, let's delve deeper into your inquiry about why __init__() is always called after __new__(). __new__() is designed to return a new instance of the class being created. After __new__() has created the instance, it is passed as a parameter to __init__() for initialization. This sequential execution ensures that __init__() can access and modify the instance's attributes after it has been successfully constructed.

In your provided example, you might be wondering why __init__() is not executed for existing instances (e.g., a2 and a3). This is because you have implemented custom logic in __new__() that checks for an existing instance in the _dict dictionary and returns it if one is found. In these cases, __init__() is skipped because the instance has already been created and initialized previously.

To implement your intended functionality differently, you could consider using a standard factory pattern instead of modifying __new__(). A factory pattern allows you to separate the creation of an object from its implementation, providing greater flexibility and reusability in your code.

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