Difference Between str and repr in Python

1. Introduction

In Python, str and repr are two methods that are used to represent objects as strings. The str function is meant to return representations of objects that are readable and appealing to human eyes. In contrast, repr is used to produce a string representation of an object that is more technical and is often valid Python code that can be used to recreate the object.

2. Key Points

1. Audience: str is for a human-readable representation, repr for a developer-centric and detailed representation.

2. Purpose: str emphasizes readability, repr emphasizes accuracy, and sometimes includes more detail.

3. Return Value: str might be less detailed, repr aims to return a string that, when passed to eval(), could recreate the object.

4. Default Implementation: If not defined, str uses repr, while repr needs explicit implementation.

3. Differences

Aspect str repr
Audience Human-readable Developer-centric
Purpose Emphasizes readability Emphasizes accuracy
Return Value Maybe less detailed Can recreate the object
Default Implementation Uses repr if not defined Needs explicit implementation

4. Example

class MyObject:
    def __init__(self, name):
        self.name = name

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

    def __repr__(self):
        return f'MyObject({self.name!r})'

obj = MyObject('Python')

# Using str
str_output = str(obj)

# Using repr
repr_output = repr(obj)

Output:

str Output:
MyObject named Python
repr Output:
MyObject('Python')

Explanation:

1. The str output provides a readable description, showing just the name of the object.

2. The repr output looks like the Python code to recreate the object, showing the class name and the name in a format that could be used to reconstruct the object.

5. When to use?

- Use str when you need a readable representation of an object, like in print statements or in user interfaces.

- Use repr when you need an unambiguous representation of an object that is more for debugging and development, potentially including more detailed information about the object.

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