What is the "repr" method in Python?

Table of Contents

• Introduction
• Understanding the __repr__ Method
  • What is the __repr__ Method?
    • Syntax:
  • Differences Between __repr__ and __str__
• Practical Use of the __repr__ Method
  • Providing Detailed Information
  • When to Use __repr__
• Practical Examples
  • Example 1: Custom __repr__ for a Simple Class
  • Example 2: Using __repr__ for Debugging
  • Example 3: Default __repr__ Behavior
• Conclusion

Introduction

In Python, the __repr__ method provides a string representation of an object that is intended to be unambiguous and useful for developers. Unlike the __str__ method, which is designed to be readable to end-users, __repr__ is meant to return a string that would ideally allow developers to recreate the object. It plays an important role in debugging, logging, and object introspection.

Understanding the __repr__ Method

What is the __repr__ Method?

The __repr__ method is a built-in function in Python that returns a string representation of an object for debugging purposes. The goal of __repr__ is to provide a string that, when passed to eval(), would recreate the object. If this is not possible or practical, the string should provide enough detail to give developers insight into the object’s contents.

Syntax:

Differences Between __repr__ and __str__

• Purpose:
  • __repr__: Focuses on providing a detailed, unambiguous string representation for developers.
  • __str__: Focuses on providing a readable string representation for users.
• Use Cases:
  • __repr__: Used for debugging and logging, and is called when you invoke repr() or inspect objects in an interactive shell.
  • __str__: Used when you want a clean, user-friendly representation, and is called by print() or str().

Practical Use of the __repr__ Method

Providing Detailed Information

When overriding __repr__, you can include detailed information about the object’s internal state. This is especially useful when inspecting objects during development or debugging.

Here, the __repr__ method gives a detailed output that could be used to recreate the object.

When to Use __repr__

• Debugging: When you need to inspect objects and their attributes to understand the code’s behavior.
• Logging: Provides detailed logs for better traceability during runtime.
• Object Inspection: In interactive shells like IPython or Jupyter notebooks, __repr__ is used when displaying objects.

Practical Examples

Example 1: Custom __repr__ for a Simple Class

Output:

In this example, the __repr__ method provides a detailed string that shows the internal state of the Dog object.

Example 2: Using __repr__ for Debugging

Here, __repr__ is useful for debugging the Rectangle object by clearly displaying the object's dimensions.

Example 3: Default __repr__ Behavior

By default, if __repr__ is not overridden, Python provides a generic representation that includes the class name and memory address.

Conclusion

The __repr__ method in Python is a valuable tool for creating detailed and unambiguous string representations of objects, primarily for developers. It helps with debugging, logging, and object introspection by providing insight into an object’s internal state. While similar to __str__, the __repr__ method is more focused on providing information that can help developers understand and potentially recreate the object. By overriding __repr__, you can make your classes more developer-friendly and easier to work with.