__init_subclass__ — Easy Examples

Called when a class is subclassed; hook for parent class customization

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Implementing __init_subclass__

Basic implementation of __init_subclass__ in a class.

python
class Example:
    def __init_subclass__(self):
        return "Example __init_subclass__"

obj = Example()
print(obj)

__init_subclass__ called when a class is subclassed; hook for parent class customization. Implementing it lets you customize how Python interacts with your objects.

__init_subclass__ in action

Seeing __init_subclass__ called by Python's built-in operations.

python
# How Python calls __init_subclass__ automatically
class Demo:
    def __init__(self, value):
        self.value = value

    def __init_subclass__(self):
        print(f"__init_subclass__ was called!")
        return self

d = Demo(42)
# This triggers __init_subclass__:
print(d)

Python automatically calls __init_subclass__ when you use the corresponding operator or function on your object.

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