What is the role of Python’s hash and eq methods?

Photo by Brecht Corbeel on Unsplash

Python provides two key methods for dealing with object comparison and hashing: __eq__ and __hash__. These methods play a crucial role in how objects are compared, stored, and retrieved in data structures like sets and dictionaries.

__eq__ - Object Equality Comparison

The __eq__ method is used to define how two instances of a class are compared for equality. By overriding this method, you specify the conditions under which two objects of a class should be considered equal.

For example:

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def __eq__(self, other):
        return self.name == other.name and self.age == other.age

In the Person class, two Person objects are considered equal if their names and ages match.

__hash__ - Object Hashing

The __hash__ method provides a way to generate a unique integer hash for an object. This is particularly important for data structures like dictionaries and sets, where objects are stored based on their hash values. For a class to be hashable, its instances must produce a consistent hash value, meaning that if two objects are equal (according to __eq__), they should have the same…