Question

What is the purpose of the __str__ method?

Short answer

The __str__ method in Python is a special method used to define a human-readable representation of an object. It is called by built-in Python functions like print() and str() to convert an object into a string for display or output purposes. Overriding the __str__ method in custom classes allows developers to provide a more informative and readable representation of their objects. This enhances the user and developer experience when interacting with those objects.

Step-by-step solution

Define the __str__ method

The __str__ method is a special method in Python, used to define a human-readable representation of an object. It is called by a few built-in Python functions, such as print() and str(), to convert an object into a string for display or output purposes.

Understand the default implementation

By default, the __str__ method returns a string that contains the name of the class of the object, along with a unique identifier. This default representation might not be very informative or user-friendly. For example, for an object of a custom class "SpaceShip", the default implementation could return a string like "".

Overriding the __str__ method

In most cases, you would want to provide a more informative and readable representation of your object. To achieve this, you can override the __str__ method in your custom class definition, by defining a new method called __str__ that returns a string representation of the object. For example, for a custom class "SpaceShip" with attributes "name" and "speed", you can implement the __str__ method as follows: ```python class SpaceShip: def __init__(self, name, speed): self.name = name self.speed = speed def __str__(self): return f"SpaceShip '{self.name}' with speed {self.speed} km/s" ```

How the __str__ method is used

The overridden __str__ method will be automatically called by various built-in Python functions, such as print() and str(), when they are used with an object of your custom class. For example, when you try to print an object of the "SpaceShip" class, you would get a user-friendly string output like this: ```python space_ship = SpaceShip("Millennium Falcon", 1050) print(space_ship) # Output: SpaceShip 'Millennium Falcon' with speed 1050 km/s ``` The __str__ method ensures that users and developers interacting with your custom classes can easily understand and interact with objects of it, by providing meaningful string representations.