跟着我们一起学 Python 30天课程-第13天-Decorators

def multiplier(num1, num2):
  return num1 * num2

some_variable = multiplier # (a reference to the function is created)

del multiplier # (deletes the function)

print(some_variable(2,4)) # 8 (still able to call the function!)

def logger(func, args):  # higher order function
    print(f'The result of the passed function is {func(*args)}')

def sum(num1, num2):
    return num1 + num2

logger(sum, (1, 5))

def random(): # Higher order function
  def special():
    print('I am something special')
  return special

random_value = random()
random_value() # I am something special
# One line way
random()() # I am something special

def starmaker(func):
  '''
  A decorator function which accepts a function
  and then wraps some goodness into it and
  returns it back!
  '''
  def wrapper():
    func()
    print('You are a star now!')
    print('*********')
  return wrapper

@starmaker
def layman():
  print('I am just a layman')

layman()

def starmaker(func):
  '''
  A decorator function which accepts a function
  and then wraps some goodness into it and
  returns it back!
  '''
  def wrapper():
    func()
    print('You are a star now!')
    print('*********')
  return wrapper

def layman():
  print('I am just a layman')

starmaker(layman)() # This is the underlying decorator magic!

def emojifier(func):
  def wrapper(emoji):
    # kwags are keyword arguments
    print(emoji)
    func()
  return wrapper

@emojifier
def random():
  pass

random('😀') # 😀

# Create an @authenticated decorator that only allows 
# the function to run is user1 has 'valid' set to True:
test_user = {
    'name': 'Jackson',
    'valid': True
}

another_user = {
  'name': 'Nathan',
  'valid': False
}

def authenticated(fn):
  def wrapper(*args, **kwargs):
    if args[0]['valid']:
      fn(args)
  return wrapper

@authenticated
def message_friends(user):
    print('message has been sent')

message_friends(test_user) # message has been sent
message_friends(another_user) # (Does nothing)