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8: Inside Class
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Summary
============
- __new__ is automatically called to create the instance
- __init__ is called after __new__ to add instance attributes to the new instance
- __new__ generally works by calling the superclass __new__ to create an instance, but you can use any mechanism that creates an object
- As long as the object is of the same type as the class or is subtype the __init__ method is called
- One standard example of how __new__ can be used is to create a singleton, a class that can only be initialized once
- Another use of __new__ is to customize immutable data objects
- Adding a custom __call__ method can be used to convert any object into a callable
    - This is how class is converted to a callable

Program
============

.. literalinclude:: programs/chapterEight.py
   :language: python

Program Output
=================

.. code-block:: console

    (docs-env) root@BMitchellLTOP:~/git/sphinx_students/source/programming_lang/book/programs# python3 chapterEight.py
    ---- Basic Example ----
    __new__ called: Creating instance
    __init__ called: Initializing instance
    Name: Brayden

    ---- Singleton Example ----
    Creating new Singleton instance
    Value: 10
    Using existing Singleton instance
    Value: 20
    Are s1 and s2 the same object? True

    ---- Immutable Customization Example ----
    Customizing immutable int
    Customizing immutable int
    num1: 5
    num2 (negative converted to 0): 0

    ---- __call__ Example ----
    Calling object like a function:
    double(5) = 10
    double(10) = 20