Understanding __str__ vs __repr__

Imagine you created a custom class in Python and want to print objects in a readable way.
Should you implement __str__ or __repr__? Let’s see the difference.

str: user-friendly representation

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

    def __str__(self):
        return f"{self.name}, {self.age} years old"

p = Person("Alice", 30)
print(p)

# Alice, 30 years old

__str__ is what print() shows — aimed at end users.

repr: unambiguous representation

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

    def __repr__(self):
        return f"Person(name={self.name!r}, age={self.age!r})"

p = Person("Alice", 30)
print(repr(p))

# Person(name='Alice', age=30)

__repr__ is used for developers/debugging. Ideally, it should look like valid Python code.

Both together

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

    def __str__(self):
        return f"{self.name}, {self.age} years old"

    def __repr__(self):
        return f"Person(name={self.name!r}, age={self.age!r})"

p = Person("Bob", 25)
print(p)        # str
print(repr(p))  # repr

Conclusion

• Use __str__ for user-friendly display (e.g., in UI, reports).
• Use __repr__ for debugging and dev tools.
• If only one is defined, __repr__ is the safer choice, since it’s used as a fallback.