Setters & Property Decorators

NITIN GUPTA

 In today’s tutorial, we are going over four main topics, i.e., Getter, Setter, Deleter, and Property decorator. Let us start with the property decorator. Before discussing property decorators, we must have an understanding of decorators themselves. Decorators are functions that take another function as an argument, and their purpose is to modify the other function without changing it.

Note: For more information, visit Tutorial #51, which is solely based on decorators. 

A property decorator is a built-in function in Python. Property decorator is a pythonic way to use getters and setters in object-oriented programming, which comes from the Python property class. Theoretically speaking, Python property decorator is composed of four things, i.e., getter, setter, deleted, and Doc. The first three are methods, and the fourth one is a docstring or comment.

 @property
 #def getter method

 Use @property along with the getter method to access the value of the attribute.

A property decorator is used for setting the parameters. In OOP, the setter is an important part of the program as we can easily get the values passed in parameters. Without a setter, it is impossible to update the values passed as parameters during object creation. Setters are usually used in Oop to set the value of private attributes in a class. 

Setters are a great way of performing encapsulation that we discussed in Tutorial #59 of our Python Tutorials for beginners course. So by using setter, our interaction gets limited to the decorator, making the use of encapsulation concept, which is the basis of Oop. We can set new values for a newer object or update values for an older one.

@function_name.setter
#def function

 @function_name.setter is a setter method with which we can set the value of the attribute

Deleter is used to delete the values passed as a parameter before. We can use a setter if we want to update or change the value, but we can not use it to delete the value. This is where deleter comes in; it removes the previous value and sets the variable equal to none. As in OOP, we do not completely erase the existence of some variable but sets it equal to none.

 # Deleter method 
@function_name.deleter

@function_name.deleter is a deleter method which can delete the assigned value by the setter method

Advantages of @property in Python:

Following are some advantages of using @property in Python:

  • The syntax of defining @property is very concise and readable.
  • We can access instance attributes while using the getters and setter to validate new values. This will avoid accessing or modifying the data directly.
  • By using @property, we can reuse the name of a property. This will prevent us from creating new names for the getters, setters, and deleters.

Summary:

In this tutorial, we have learned about property decorators, setters, getters, and deleters. Property decorator(@property) is a pythonic way of defining getters, setters, and deleters. Properties defined with the @property syntax is more compact and readable. When we define the properties, we can change the class’s internal implementation without changing the program.

Code as described/written in the video


class Employee:
    def __init__(self, fname, lname):
        self.fname = fname
        self.lname = lname
        # self.email = f"{fname}.{lname}@codewithharry.com"

    def explain(self):
        return f"This employee is {self.fname} {self.lname}"

    @property
    def email(self):
        if self.fname==None or self.lname == None:
            return "Email is not set. Please set it using setter"
        return f"{self.fname}.{self.lname}@codewithharry.com"

    @email.setter
    def email(self, string):
        print("Setting now...")
        names = string.split("@")[0]
        self.fname = names.split(".")[0]
        self.lname = names.split(".")[1]

    @email.deleter
    def email(self):
        self.fname = None
        self.lname = None


hindustani_supporter = Employee("Hindustani", "Supporter")
# nikhil_raj_pandey = Employee("Nikhil", "Raj")

print(hindustani_supporter.email)

hindustani_supporter.fname = "US"

print(hindustani_supporter.email)
hindustani_supporter.email = "this.that@codewithharry.com"
print(hindustani_supporter.fname)

del hindustani_supporter.email
print(hindustani_supporter.email)
hindustani_supporter.email = "Harry.Perry@codewithharry.com"
print(hindustani_supporter.email)

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