Python property() is a built-in function that returns a property attribute for classes.

Python property() Syntax

property(fget=None, fset=None, fdel=None, doc=None)

Where,

• fget (optional) – Function for getting the attribute value
• fset (optional) – Function for setting an attriibute value
• fdel (optional) – Function for deleting an attribute value
• doc (optional) – It is the documentation string(docstring) of the property attribute

The property() function is used to provide methods to control the access of attributes. Using property()function we can bind the getter, setter and deleter function altogether or individually with an attribute name.

To create a property, we define the instance variable and one or more method functions.

Python property() Example

Now let’s see how property() is used in Python with a program to convert currency (currency_y = currency_x  * 28).

class CurrencyConverter:
 
 def __init__(self, currency_x = 1):
   self.currency_x = currency_x

 def currency_converter(self):
   currency_y = self.get_currency_x() * 28
   return (currency_y)

 #implementing new getter method
 def get_currency_x(self):
   print ('inside getter method')
   return (self._currency_x)

 #implementing new setter method
 def set_currency_x(self, currency_value):
   if currency_value < 0:
     raise ValueError("Currency can't be negative")
   print ('inside setter method')
   self._currency_x = currency_value

 currency_x = property(get_currency_x, set_currency_x)

Now, let’s try to get, set and convert the value of the currency.

Output

>>> #Creating new object
>>> c = CurrencyConverter(2)
inside setter method

>>> #get the value of currency_x using getter method
>>> c.get_currency_x()
inside getter method
2

>>> #converting the currency
>>> c.currency_converter()
inside getter method
56

In above example, the property() function attaches the defined getter and setter methods to the variable currency_x. Now, whenever a value is assigned to currency_x, set_currency_x() method will be automatically invoked.