Decorators

A decorator is a function that wraps another function to enhance or modify its behavior.
Decorators are only possible because of the ability of functions to act like variables
A decorator supercharges the function.
Its a func that wraps another func and enhances or changes it.

Creating a Decorator

def my_decorator(func):
    def wrap_func():             #inner function, with parameter x
        print('**********')      #extra functionality
        func()                   #calling the original function
        print('**********')      #extra functionality
    return wrap_func             #returning the inner function

@my_decorator
def bye():            # We are decorating bye function
    print()           # We've super boosted our bye.

bye()                 # we are actually calling wrap_func inside my_decorator

what it does: variable = my_decorator(func) func()

my_decorator(bye)()    # same as above

DECORATOR PATTERN

Decorators can accept any number of arguments using args and *kwargs.

def decorator(func):
    def wrap_func(*args, **kwargs):     #can add infinite parameters
        func(*args, **kwargs)
    return wrap_func

@decorator
def hey(greeting, emoji=':)'):
    print(greeting, emoji)

hey('yoooo')

Performance Example

Measure execution time using a decorator of a program.

from time import time

def performance(fn):
    def wrapper(*args, **kwargs):
        st = time()
        fn(*args, **kwargs)
        ed = time()
        print(f'took {ed-st} ms')
    return wrapper

@performance
def long_time():
    print(1)
    for i in range(500):
        return i*5

long_time()