What is the purpose of the __str__() method in Python?

The __str__() method in Python is a special method that is called by the str() built-in function and by Python's print statement to compute the "informal" or nicely printable string representation of an object. It returns a string that represents the object.

The __str__() method takes the self parameter, which refers to the object whose string representation is being computed. It must return a string object.

For example, consider the following code:

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

    def __str__(self):
        return f"{self.name}, {self.age} years old"

person = Person("Alice", 30)
print(person)

In this example, the Person class defines a __str__() method that returns a string representation of the object. The __str__() method uses an f-string to format the name and age attributes of the object as a string.

When the print() function is called with the person object, it automatically calls the __str__() method to compute the string representation of the object. This prints the string "Alice, 30 years old".

By using the __str__() method, the Person class can define a custom string representation for objects of the class. This makes the code more readable and makes it easier to debug and understand the behavior of the code.