Method Resolution Order (MRO) in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Method Resolution Order (MRO) in Python?

MRO is the order in which Python looks for a method in a hierarchy of classes when you call it. It decides which method to run first when multiple classes have the same method name.

intermediate

How does Python determine the MRO for new-style classes?

Python uses the C3 linearization algorithm to create a consistent order of classes to search for methods, ensuring that subclasses come before their parents and preserving the order of base classes.

beginner

What does the __mro__ attribute show in a Python class?

The <code>__mro__</code> attribute is a tuple that shows the order in which Python will look for methods in the class hierarchy.

intermediate

What happens if there is a conflict in method names in multiple inheritance?

Python uses the MRO to decide which method to call. It picks the first method it finds following the MRO order, so the method in the class that appears earlier in the MRO is used.

beginner

How can you view the MRO of a class in Python?

You can view the MRO by using the ClassName.__mro__ attribute or the built-in function help(ClassName) which shows the method resolution order.

What does MRO stand for in Python?

A Method Return Output

B Method Resolution Order

C Module Runtime Operation

D Memory Reference Object

MRO stands for Method Resolution Order, which is the order Python follows to find methods in class inheritance.

Which algorithm does Python use to determine MRO for new-style classes?

A C3 linearization

B Depth-first search

C Breadth-first search

D Topological sort

Python uses the C3 linearization algorithm to create a consistent MRO.

What will ClassName.__mro__ return?

A A tuple of classes in the order Python searches for methods

B The list of all methods in the class

C The memory address of the class

D The source code of the class

__mro__ shows the order of classes Python checks for methods.

If two parent classes have the same method, which one is called?

A Both methods are called

B The method from the last parent class listed

C The method from the class that appears first in the MRO

D Python raises an error

Python calls the method from the class that comes first in the MRO.

How can you check the MRO of a class quickly?

A Use <code>print(ClassName)</code>

B Use <code>type(ClassName)</code>

C Use <code>dir(ClassName)</code>

D Use <code>ClassName.__mro__</code>

The __mro__ attribute shows the method resolution order.

Explain what Method Resolution Order (MRO) is and why it is important in Python.

Think about how Python decides which method to run when multiple classes have the same method.

Describe how Python determines the MRO for a class with multiple parents.

Consider the algorithm Python uses to keep the order consistent and predictable.