Comparison magic methods in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the __eq__ magic method in Python?

The __eq__ method defines how two objects are compared for equality using the == operator.

beginner

Which magic method is called when using the < operator?

The __lt__ method is called to check if one object is less than another.

intermediate

How does Python use __le__ and __ge__ methods?

__le__ defines behavior for the <= operator (less than or equal), and __ge__ defines behavior for the >= operator (greater than or equal).

intermediate

What happens if you only define __eq__ but not __ne__?

Python will automatically infer __ne__ (not equal) as the opposite of __eq__, so you usually don't need to define __ne__ separately.

beginner

Why would you implement comparison magic methods in your own class?

To allow objects of your class to be compared using standard operators like <code>==</code>, <code>&lt;</code>, <code>&gt;</code>, which helps with sorting, searching, and logical checks.

Which magic method is used for the 'greater than' (>) comparison?

A __gt__

B __ge__

C __lt__

D __le__

The __gt__ method defines behavior for the > operator.

If you want to check if two objects are not equal, which magic method is used?

A __gt__

B __eq__

C __lt__

D __ne__

The __ne__ method defines behavior for the != operator.

What does the __le__ method represent?

A Less than (<)

B Less than or equal (<=)

C Greater than (>)

D Greater than or equal (>=)

__le__ is for the <= operator.

If a class defines __eq__ but not __ne__, what happens when != is used?

A __ne__ is automatically the opposite of __eq__

B Error is raised

C __ne__ returns True always

D Comparison always returns False

Python automatically uses the opposite of __eq__ for __ne__ if not defined.

Which magic method would you implement to allow sorting objects with the < operator?

A __eq__

B __ne__

C __lt__

D __gt__

The __lt__ method defines behavior for the < operator, which is used in sorting.

Explain the role of comparison magic methods in Python and name at least three of them.

Think about how Python knows what to do when you use ==, <, or > with objects.

Describe what happens if you define __eq__ but not __ne__ in a Python class.

Consider how Python handles != when __ne__ is missing.