[decorator]Python decorator #python

decorator.py

# Use decorator to do something before or after certain function
# E.g. Timer and Certain error check

# importing time module 
from time import time 
class Timer: 
  
    def __init__(self, func): 
        self.function = func 
  
    def __call__(self, *args, **kwargs): 
        start_time = time() 
        result = self.function(*args, **kwargs) 
        end_time = time() 
        print("Execution took {} seconds".format(end_time-start_time)) 
        return result 
  
  
# adding a decorator to the function 
@Timer
def some_function(delay): 
    from time import sleep 
  
    # Introducing some time delay to  
    # simulate a time taking function. 
    sleep(delay) 
  
some_function(3) 

# class decorator 
  
class ErrorCheck: 
  
    def __init__(self, function): 
        self.function = function 
  
    def __call__(self, *params): 
        if any([isinstance(i, str) for i in params]): 
            raise TypeError("parameter cannot be a string !!") 
        else: 
            return self.function(*params) 
  
  
@ErrorCheck
def add_numbers(*numbers): 
    return sum(numbers) 
  
#  returns 6 
print(add_numbers(1, 2, 3))  
  
# raises Error.   
print(add_numbers(1, '2', 3))