create a decorator python code example

Example 1: python function decorator

#Decorator are just function that take function as first
#parameter and return a function
def logging(f):
  def decorator_function(*args, **kwargs):
    print('executing '+f.__name__)
    return f(*args, **kwargs)
  return decorator_function
#Use it like this
@logging
def hello_world():
  print('Hello World')
#calling hello_world() prints out:
#executing hello_world
#Hello World

Example 2: decorator python

def our_decorator(func):
    def function_wrapper(x):
        print("Before calling " + func.__name__)
        func(x)
        print("After calling " + func.__name__)
    return function_wrapper

@our_decorator
def foo(x):
    print("Hi, foo has been called with " + str(x))

foo("Hi")

Example 3: decorators in python

'pass function which we want to decorate in decorator callable object'
def our_decorator(func):  # func is function to be decorated by decorator
  
  def wrapper(x):       # x is parameter which is passed in func
    if x%2==0:
      return func(x)
    else:
      raise Exception("number should be even")
  return wrapper

@ our_decorator
def func(x):         # actual function 
  print(x,"is even")
func(2)
func(1)

' if you do not want to use @'
func=our_decorator(func)
func(2)