python之装饰器

def func():   # 函数名仅仅只是个绑定内存地址的变量       
	print("i`m running") 
# 这是调用                       
func()  # i`m running
# 这是对象引用，引用的是内存地址        
func2 = func  
print(func2 is func)  # True
# 通过引用进行调用  
func2()  # i`m running

def decorator_get_function_name(func):
	"""
	获取正在运行函数名
	:return:
	"""
	def wrapper(*arg):
		"""
		wrapper
		:param arg:
		:return:
		"""
		print(f"当前运行方法名：{func.__name__}  with  params: {arg}")
		return func(*arg)
	return wrapper

@decorator_get_function_name
def test_func_add(x, y):
	print(x + y)

@decorator_get_function_name
def test_func_sub(x, y):
	print(x - y)

test_func_add(1, 2)
# 当前运行方法名：test_func_add  with  params: (1, 2)
# 3
test_func_sub(3, 5)
# 当前运行方法名：test_func_sub  with  params: (3, 5)
# -2

def login_check(func):
    def wrapper(request, *args, **kwargs):
        if not request.session.get('login_status'):
            return HttpResponseRedirect('/api/login/')
        return func(request, *args, **kwargs)
    return wrapper
@login_check
def edit_config():
	pass

"""
>  1. def login_check(func):  ==>将login_check函数加载到内存
>  ....
>  @login_check  ==>此处已经在内存中将login_check这个函数执行了！；并不需要等edit_config()实例化调用
>  2. 上例@login_check内部会执行以下操作：
>	  2.1 执行login_check函数，并将 @login_check 下面的 函数(edit_config) 作为login_check函数的参数，即：@login_check 等价于 login_check(edit_config)
>     2.2 内部就会去执行：
      def wrapper(*args):
          # 校验session...
          return func(request, *args, **kwargs)   # func是参数，此时 func 等于 edit_config，此处相当于edit_config(request, *args, **kwargs)
      return wrapper     # 返回的 wrapper，wrapper代表的是函数对象，非函数实例化对象
      2.3 其实就是将原来的 edit_config 函数塞进另外一个函数中,另一个函数当中可以做一些操作；再执行edit_config
      2.4 将执行完的 login_check 函数返回值(也就是 wrapper对象)将此返回值再重新赋值给新 edit_config，即：
      2.5 新edit_config = def wrapper:
             # 校验session...
            return 原来edit_config(request, *args, **kwargs) 
>  3. 也就是新edit_config()=login_check(edit_config):wrapper(request, *args, **kwargs):return edit_config(request, *args, **kwargs) 有点绕，大家看步骤细细理解。
"""

from functools import wraps
def w1(func):
	@wraps(func)
	def wrapper(*args, **kwargs):
		print("这里是第一个校验")
		return func(*args, **kwargs)
	return wrapper

def w2(func):
	@wraps(func)
	def wrapper(*args, **kwargs):
		print("这里是第二个校验")
		return func(*args, **kwargs)
	return wrapper

def w3(func):
	def wrapper(*args, **kwargs):
		print("这里是第三个校验")
		return func(*args, **kwargs)
	return wrapper

@w2  # 这里其实是w2(w1(f1))
@w1  # 这里是w1(f1)
def f1():
	print(f"i`m f1, at {f1}")

@w3
def f2():
	print(f"i`m f2, at {f2}")
# ====================== 实例化阶段 =====================
f1()
# 这里是第二个校验
# 这里是第一个校验
# i`m f1, at <function f1 at 0x7febc52f5e50>
f2()
# 这里是第三个校验
# i`m f2, at <function w3.<lo

def decorator_get_function_duration(enable):
	"""
	:param enable:  是否需要统计函数执行耗时
	:return: 
	"""
	print("this is decorator_get_function_duration")
	def inner(func):
		print('this is inner in decorator_get_function_duration')
		@wraps(func)
		def wrapper(*args, **kwargs):
			print('this is a wrapper in decorator_get_function_duration.inner')
			if enable:
				start = time.time()
				print(f"函数执行前：{start}")
				result = func(*args, **kwargs)
				print('[%s]`s enable was %s it`s duration : %.3f s ' % (func.__name__, enable, time.time() - start))
			else:
				result = func(*args, **kwargs)
			return result
		return wrapper
	return inner

def decorator_1(func):
	print('this is decorator_1')
	@wraps(func)
	def wrapper(*args, **kwargs):
		print('this is a wrapper in decorator_1')
		return func(*args, **kwargs)
	return wrapper

def decorator_2(func):
	print('this is decorator_2')
	@wraps(func)
	def wrapper(*args, **kwargs):
		print('this is a wrapper in decorator_2')
		return func(*args, **kwargs)
	return wrapper

@decorator_1 # 此处相当:decorator_1(decorator_2(decorator_get_function_duration(enable=True)(fun)))
@decorator_2 # = decorator_2(decorator_get_function_duration(enable=True)(fun))
@decorator_get_function_duration(enable=True)  # = decorator_get_function_duration(enable=True)(fun)
def fun():
	time.sleep(2)
	print("fun 执行完了～")

fun()
# ======== enable=False ============
"""
this is decorator_get_function_duration
this is inner in decorator_get_function_duration
this is decorator_2
this is decorator_1
this is a wrapper in decorator_1
this is a wrapper in decorator_2
this is a wrapper in decorator_get_function_duration.inner
fun 执行完了～
"""
# ======== enable=True ============
"""
this is decorator_get_function_duration
this is inner in decorator_get_function_duration
this is decorator_2
this is decorator_1
this is a wrapper in decorator_1
this is a wrapper in decorator_2
this is a wrapper in decorator_get_function_duration.inner
函数执行前：1634635708.648994
fun 执行完了～
[fun]`s enable was True it`s duration : 2.002 s 
"""