Should I Avoid Multiple Inheritance in My Code?

Should I Avoid Multiple Inheritance?

Multiple inheritance (MI) is a programming concept that allows a class to inherit from multiple parent classes. While it may seem like a convenient way to combine features, it can often lead to maintenance nightmares.

Why Avoid Multiple Inheritance?

1. Composition over Inheritance:
Consider using composition instead of inheritance when possible. Composition allows you to combine objects with different functionalities without incurring the complexities of MI.

2. The Diamond of Dread:
MI can create the "Diamond of Dread" scenario, where a class inherits from two classes that inherit from a common ancestor. This can lead to ambiguity and conflicts in method resolution.

3. Ambiguity with Virtual Inheritance:
In object hierarchies, the inheritance graph should ideally be a tree, not a graph. MI can introduce ambiguity when inheriting from multiple interfaces that share similar methods.

When to Consider MI

Despite its drawbacks, MI may be appropriate in certain scenarios:

1. Unrelated Classes:
If the classes in question are completely unrelated and serve distinct purposes, then MI may simplify implementation.

2. Private Inheritance:
Private inheritance can be used to implement implementation details without exposing them publically, reducing the risks associated with MI.

3. C Idioms:
Some C idioms, such as policies, utilize MI to achieve specific design goals.

Conclusion

While MI can be a convenient option, it should be used with caution. Most of the time, composition or single inheritance is preferred to avoid the complexities and pitfalls associated with MI. Be prepared to defend your use of MI in code reviews and consider alternative approaches whenever possible.

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