How to Use Getter and Setter in Python: Simple Guide

In Python, use the @property decorator to create a getter method and @.setter to create a setter method. This allows controlled access to private attributes while using simple attribute syntax.

Syntax

Use @property above a method to make it a getter. Use @property_name.setter above another method to make it a setter for the same attribute.

This lets you access and set the attribute like a normal variable but with extra control.

python

class MyClass:
    def __init__(self, value):
        self._value = value  # private attribute

    @property
    def value(self):
        return self._value

    @value.setter
    def value(self, new_value):
        self._value = new_value

Example

This example shows how to use getter and setter to control access to a private attribute _age. The setter checks that the age is not negative.

python

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

    @property
    def age(self):
        return self._age

    @age.setter
    def age(self, value):
        if value < 0:
            raise ValueError("Age cannot be negative")
        self._age = value

p = Person(25)
print(p.age)  # prints 25
p.age = 30
print(p.age)  # prints 30

try:
    p.age = -5
except ValueError as e:
    print(e)

Output

25
30
Age cannot be negative

Common Pitfalls

One common mistake is forgetting to use the @property decorator, which means the method won't act like an attribute.

Another is not using a private attribute (like _value) inside the getter and setter, causing infinite recursion.

python

class Wrong:
    def __init__(self, value):
        self.value = value

    def value(self):  # Missing @property
        return self.value  # Causes infinite recursion

class Right:
    def __init__(self, value):
        self._value = value

    @property
    def value(self):
        return self._value

    @value.setter
    def value(self, new_value):
        self._value = new_value

Quick Reference

• @property: Makes a method act like a getter.
• @property_name.setter: Defines the setter for the property.
• Use a private attribute (like _attr) to store the actual value.
• Access the property like a normal attribute (no parentheses).

Key Takeaways

Use @property to create a getter method that looks like an attribute.

Use @property_name.setter to create a setter method for controlled attribute assignment.

Always store the real value in a private attribute to avoid recursion.

Access properties like normal attributes without parentheses.

Setters can include validation or extra logic before assigning values.