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Python property() function

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Python property() function returns the object of the property class and it is used to create the property of a class.  In Python, the property() function is a built-in function that allows us to create a property for a class. In this article, we will learn more about the Python property() function.

Python property() Function Syntax

Python property() function is used to create a class property in Python.

Syntax: property(fget, fset, fdel, doc)

Parameters: 

  • fget() – used to get the value of attribute
  • fset() – used to set the value of attribute
  • fdel() – used to delete the attribute value
  • doc() – string that contains the documentation (docstring) for the attribute

Return: Returns a property attribute from the given getter, setter and deleter.

Note:

  • If no arguments are given, property() method returns a base property attribute that doesn’t contain any getter, setter, or deleter.
  • If doc isn’t provided, property() method takes the docstring of the getter function.

What is property() Function in Python

Python property() function is a built-in function that allows us to create a special type of attribute called a property for a class. Properties are used to encapsulate the access to an object attribute and to add some logic to the process such as computation, access control, or validation.

Python property() Function Methods

Below are the ways by which we can create property for a class in Python:

  • Using property() method
  • Using @property decorator

Using property() Method 

In this example, we are using the property() function to create a class property in Python. We define a class called Alphabet, and within this class, we create a property named value to encapsulate access to an internal attribute _value. This property allows us to control how the _value attribute is accessed and modified by providing custom getter and setter methods.

Python3

# Python program to explain property() function
# Alphabet class
 
class Alphabet:
    def __init__(self, value):
        self._value = value
 
    # getting the values
    def getValue(self):
        print('Getting value')
        return self._value
 
    # setting the values
    def setValue(self, value):
        print('Setting value to ' + value)
        self._value = value
 
    # deleting the values
    def delValue(self):
        print('Deleting value')
        del self._value
 
    value = property(getValue, setValue,
                     delValue, )
 
 
# passing the value
x = Alphabet('GeeksforGeeks')
print(x.value)
 
x.value = 'GfG'
 
del x.value

                    

Output
Getting value
GeeksforGeeks
Setting value to GfG
Deleting value



Using @property Decorator

The main work of decorators is they are used to add functionality to the existing code. Also called metaprogramming, as a part of the program tries to modify another part of the program at compile time. First, specify that value() method is also an attribute of Alphabet then, we use the attribute value to specify the Python property setter and the deleter. Notice that the same method value() is used with different definitions for defining the getter, setter, and deleter. Whenever we use x.value, it internally calls the appropriate getter, setter, and deleter.

Python3

# Python program to explain property()
# function using decorator
 
class Alphabet:
    def __init__(self, value):
        self._value = value
 
    # getting the values
    @property
    def value(self):
        print('Getting value')
        return self._value
 
    # setting the values
    @value.setter
    def value(self, value):
        print('Setting value to ' + value)
        self._value = value
 
    # deleting the values
    @value.deleter
    def value(self):
        print('Deleting value')
        del self._value
 
 
# passing the value
x = Alphabet('Peter')
print(x.value)
 
x.value = 'Diesel'
 
del x.value

                    

Output
Getting value
Peter
Setting value to Diesel
Deleting value



Python Property vs Attribute

Class Attribute: Class Attributes are unique to each class. Each instance of the class will have this attribute. In the given example, the count variable is a class attribute.

Python3

# declare a class
class Employee:
 
    # class attribute
    count = 0
 
    # define a method
    def increase(self):
        Employee.count += 1
 
# create an Employee
# class object
a1 = Employee()
 
# calling object's method
a1.increase()
 
# print value of class attribute
print(a1.count)
 
a2 = Employee()
 
a2.increase()
 
print(a2.count)
 
print(Employee.count)

                    

Output
1
2
2



Python property(): Returns object of the property class. In this example, we are demonstrating the use of property() function.

Python3

# create a class
class gfg:
     
    # constructor
    def __init__(self, value):
        self._value = value
             
    # getting the values
    def getter(self):
        print('Getting value')
        return self._value
             
    # setting the values
    def setter(self, value):
        print('Setting value to ' + value)
        self._value = value
             
    # deleting the values
    def deleter(self):
        print('Deleting value')
        del self._value
     
    # create a properties
    value = property(getter, setter, deleter, )
     
# create a gfg class object
x = gfg('Happy Coding!')
print(x.value)
     
x.value = 'Hey Coder!'
     
# deleting the value
del x.value

                    

Output
Getting value
Happy Coding!
Setting value to Hey Coder!
Deleting value



Applications

By using property() method, we can modify our class and implement the value constraint without any change required to the client code. So that the implementation is backward compatible.



Last Updated : 29 Nov, 2023
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