What is Method Resolution Order (MRO) in Python?

What is Method Resolution Order (MRO) in Python?

Method Resolution Order (MRO) is the order in which base classes are searched when executing a method. In Python, MRO is crucial for understanding how methods are inherited in classes, especially with multiple inheritance.

Can you give me an example of MRO in Python?

Sure! Consider the following classes:

class A:
    def method(self):
        return 'A'

class B(A):
    def method(self):
        return 'B'

class C(A):
    def method(self):
        return 'C'

class D(B, C):
    pass

print(D.mro())

This will output the MRO: [<class '__main__.D'>, <class '__main__.B'>, <class '__main__.C'>, <class '__main__.A'>, <class 'object'>]. It shows the order in which Python will look for methods.

What happens if I call D().method()?

If you call D().method(), it will return 'B' because class D inherits from B first, and B's method is found before C's method in the MRO.

How can I visualize the MRO?

You can visualize the MRO using the mro() method or the super() function. Additionally, tools like pyreverse can help create UML diagrams to represent class hierarchies.