Property Decorators in Python Made Easy

Property decorators in Python allow you to define getter, setter, and deleter methods for a class attribute. They are used to control access to the attribute and can be useful in many cases, such as data validation, property-based methods, and more. The @property decorator is used to define a getter method, the @attribute_name.setter decorator is used to define a setter method, and the @attribute_name.deleter decorator is used to define a deleter method.

Here are a few examples of property decorators in Python:

Example 1:

class Circle:
    def __init__(self, radius):
        self._radius = radius
        
    @property
    def radius(self):
        return self._radius
    
    @radius.setter
    def radius(self, value):
        if value < 0:
            raise ValueError("Radius cannot be negative")
        self._radius = value
        
        
first_circle = Circle(-5)
second_circle = Circle(5)
print(first_circle.radius)  # Output: -5
print(second_circle.radius) # Output: 5
first_circle.radius = 6
print(first_circle.radius)  # Output: 6
second_circle.radius = -57
print(second_circle.radius)  
'''
Output: raceback (most recent call last):
  File "<string>", line 22, in <module>
  File "<string>", line 12, in radius
ValueError: Radius cannot be negative */
'''

In the above example, the Circle class has an radius attribute that can be set only to a positive value. If a negative value is passed, a ValueError will be raised. The @property decorator allows us to access the radius attribute directly, without having to use a method. The @radius.setter decorator allows us to set the radius attribute, and the setter method is used to validate the input.

Example 2:

class Temperature:
    def __init__(self, celsius):
        self._celsius = celsius
        
    @property
    def celsius(self):
        return self._celsius
    
    @celsius.setter
    def celsius(self, value):
        self._celsius = value
        
    @property
    def fahrenheit(self):
        return (self._celsius * 1.8) + 32

In this example, the Temperature class has two attributes, celsius and fahrenheit. The celsius the attribute can be set and retrieved directly, while the fahrenheit attribute can only be retrieved. The fahrenheit property is calculated based on the celsius attribute using the formula (celsius * 1.8) + 32.