__init__ — Easy Examples

Constructor; called when a new instance is created to initialize its attributes

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Implementing __init__

Basic implementation of __init__ in a class.

python
class Dog:
    def __init__(self, name, breed):
        self.name = name
        self.breed = breed

    def __str__(self):
        return f"{self.name} ({self.breed})"

dog = Dog("Rex", "German Shepherd")
print(dog)
print(dog.name)

__init__ constructor; called when a new instance is created to initialize its attributes. Implementing it lets you customize how Python interacts with your objects.

__init__ in action

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

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

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

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

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

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