What are decorators in Python?

A Decorator is one of the most powerful design patterns in Python. Decorator is used to add new features to an already created object without modifying its structure. With Decorators, you can easily wrap another function for extending the wrapped function beh**iour and this is done without modifying it permanently.

Functions are first-class objects

In Python, the functions are considered as first-class objects i.e. we can store the functions in a variable, return function from a function, etc.

Below are some examples displaying functions in Python useful for understanding Decorators.

Functions as objects

Example

The functions are considered as object in this example. Here, the function demo() is assigned to a variable −

Output

tHISISIT!
hELLO

Pass the function as an argument

Example

In this the function is passed as an argument. The demo3() function calls demo() and demo2() function as a parameter.

Output

tHIS IS IT!
This is it!

Now, let us work around Decorators

Decorators in Python

In Decorators, the functions are taken as an argument into another function and then called inside the wrapper function. Let us see a quick example:

@mydecorator
   def hello_decorator():
      print("This is sample text.")

The above can also be written as −

def demo_decorator():
   print("This is sample text.")

hello_decorator = mydecorator (demo_decorator)

Decorator Example

Output

Sum = 30

Applying Syntactic Decorator

Example

The above example can be simplified using decorator with the @symbol. This eases applying decorators by placing @ symbol before the function we want to decorate −

Output

Sum = 30