How Can I Customize the String Representation of Python Class Instances?

Customizing the String Representation of Class Instances

When printing an instance of a class, the default output typically resembles <__main__.ClassName object at 0xXXXXXXXX>, which provides limited information. To customize how class instances appear when printed, it is essential to understand the concept of string representation.

String Representation Methods

Python provides two methods for controlling the string representation of classes and objects:

• __str__: Defines how the instance should be displayed when using the print() function.
• __repr__: Defines how the instance should be displayed when using the repr() function or in interactive prompts.

Overriding String Representation

To customize the string representation of a class instance, you need to override these methods within the class definition. For example:

class Test:
    def __str__(self):
        return "Customized string representation"

By providing a custom implementation of __str__, you can control the output when calling print() on an instance of the Test class.

Overriding Both String Representation Methods

In certain cases, you may want to provide different representations for printing and debugging purposes. In this scenario, you can override both __str__ and __repr__ within the class definition.

class Test:
    def __str__(self):
        return "User-friendly representation"

    def __repr__(self):
        return "Technical representation for debugging"

With this implementation, print() will display the user-friendly representation, while interactive prompts and debugging tools will show the technical representation.

Using the String Representation Methods

Once you have defined the custom string representation methods, you can use them as follows:

• To print a custom string representation:

print(instance_name)

• To view the technical string representation in interactive prompts or debugging tools:

repr(instance_name)

By overriding __str__ and __repr__, you can tailor the output of class instances to meet your specific requirements, making them more informative and useful for different purposes.

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