Custom Data Types

When you pass an object to print(), it converts it to a string using the str() function. You can create a __str__() method on your custom objects to change what is output:

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

    def __str__(self):
        return f'Person({self.name})'

Here’s what you’ll get:

>>> from person import Person
>>> john = Person('John Cleese', 80)
>>> print(john)
Person(John Cleese)

The __str__() method is meant to output a human-readable version of your object. There is also a __repr__() method, which is meant for a Python representation of the object. There is a repr() function that corresponds to the str() function. If you define your __repr__() properly, then eval() can be called on its result to create a new object.