How Should I Call Parent Class `__init__` Methods with Multiple Inheritance in Python?

Calling Parent Class init with Multiple Inheritance: The Right Approach

Multiple inheritance can be a useful technique in Python, but it can also introduce complexities when calling parent class constructors. This article investigates the correct method to invoke both parent class constructors in a child class, addressing potential issues and the need to consider the design of the inherited classes.

The Importance of Understanding Base Class Design

The primary factor to consider when calling parent class constructors is whether the base classes are designed for multiple inheritance. Three possible scenarios exist:

1. Unrelated Parent Classes:

If the base classes are standalone and not intended for multiple inheritance, they may not call super().__init__(). In this case, the child class must explicitly call each parent constructor manually, either directly or using super.

2. Mixin Class:

A mixin is designed to be used with multiple inheritance and automatically calls the subsequent parent constructor. Calling super().__init__() in the child class is sufficient to invoke all parent constructors.

3. Cooperative Parent Classes:

Cooperative classes also accept unused arguments and forward them to the next base class. Like mixins, they allow the child class to call super().__init__() and invoke all parent constructors.

Choosing the Right Approach

The appropriate method for calling parent class constructors depends on the design of the base classes:

• For unrelated parents, explicitly call each constructor.
• For mixins, call super().__init__() with all arguments.
• For cooperative parents, call super().__init__() with keyword arguments.

Conclusion

Understanding the design of inherited classes is crucial when accessing parent class constructors in multiple inheritance scenarios. By considering the specific class structure and following the appropriate approach, developers can ensure proper initialization and avoid potential issues.

The above is the detailed content of How Should I Call Parent Class `__init__` Methods with Multiple Inheritance in Python?. For more information, please follow other related articles on the PHP Chinese website!