How to call parent class init in Python?
Jul 10, 2025 pm 01:00 PM
In Python, there are two main ways to call the __init__ method of the parent class. 1. Use the super() function, which is a modern and recommended method that makes the code clearer and automatically follows the method parsing order (MRO), such as super().__init__(name). 2. Directly call the __init__ method of the parent class, such as Parent.__init__(self, name), which is useful when you need to have full control or process old code, but will not automatically follow the MRO. In multiple inheritance cases, super() should always be used consistently to ensure the correct initialization order and behavior.
In Python, calling the parent class's __init__ method is a common need when working with inheritance. If you're creating a subclass and want to make sure the initialization logic from the parent class runs properly, there are clear ways to do that.
Using super() in Python 3
The most modern and recommended way to call the parent class's __init__ is by using the super() function. This keeps your code clean and avoids hardcoding the parent class name.
For example:
class Parent:
def __init__(self, name):
self.name = name
class Child(Parent):
def __init__(self, name, age):
super().__init__(name) # Calls Parent's __init__
self.age = age Here, super().__init__(name) makes sure the Parent class initializes the name attribute.
This approach works well even if you have multiple levels of inheritance, since super() follows the method resolution order (MRO) automatically.
A few things to keep in mind:
- You don't need to pass
selfwhen usingsuper()in Python 3. - Always match the parameters expected by the parent class's
__init__.
Calling Parent Class Directly
Another option is to explicitly call the parent class's __init__ by referring to it directly.
Like this:
class Parent:
def __init__(self, name):
self.name = name
class Child(Parent):
def __init__(self, name, age):
Parent.__init__(self, name) # Explicit call
self.age = ageThis can be useful in certain situations — especially if you're dealing with older Python 2 code or multiple inheritance where you want full control.
But here's the catch:
- It doesn't follow the MRO automatically like
super()does. - If your class inherits from more than one parent class, this might cause issues unless you're careful.
So, use this method only when you know what you're doing or when you specifically need to bypass super() behavior.
Handling Multiple Inheritance
When a class inherits from multiple parents, using super() becomes even more important.
Take this example:
class A:
def __init__(self):
print("A init")
class B(A):
def __init__(self):
print("B before")
super().__init__()
print("B after")
class C(A):
def __init__(self):
print("C before")
super().__init__()
print("C after")
class D(B, C):
def __init__(self):
print("D before")
super().__init__()
print("D after") Calling D().__init__() would output based on Python's MRO:
D before B before C before A init C after B after Da after
Each __init__ runs once and in the right order thanks to super() .
If you skipped super() in any of these classes, some initializations wouldn't happen at all.
So, in multiple inheritance cases, always use super() consistently across all __init__ methods involved.
That's how you handle parent class initialization in Python. Whether you go with super() or direct calls depends on your needs, but sticking with super() is usually the safer bet.
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