详解 Python中LEGB和闭包及装饰器

def f_100(val):
  passline = 60
  if val >= passline:
    print ('pass')
  else:
    print ('failed')

def f_150(val):
  passline = 90
  if val >= passline:
    print ('pass')
  else:
    print ('failed')

f_100(89)
f_150(89)

def set_passline(passline):
  def cmp(val):
    if val >= passline:
      print ('Pass')
    else:
      print ('failed')
  return cmp

f_100 = set_passline(60)
f_150 = set_passline(90)
f_100(89)
f_150(89)

def my_sum(*arg):
  if len(arg) == 0:
    return 0
  for val in arg:
    if not isinstance(val,int): # 有一个非int则返回0
      return 0
  return sum(arg)

def my_average(*arg):
  if len(arg) == 0:
    return 0
  for val in arg:
    if not isinstance(val,int): # 有一个非int则返回0
      return 0
  return sum(arg)/len(arg)

print (my_sum(1,2,3,4,5))
print (my_sum(1,2,3,4,5,'6'))
print (my_aveage(1,2,3,4,5))
print(my_average())

def my_sum(*arg):
  return sum(arg)
def my_average(*arg):
  return sum(arg)/len(arg)

def dec(func):
  def in_dec(*arg): # my_sum
    print ('in dec arg= ',arg)
    if len(arg) ==0:
      return 0
    for val in arg:
      if not isinstance(val, int):
        return 0
    return func(*arg)  # 闭包，存在于in_dec函数中的__closure__中，所以可以调用
  return in_dec

my_sum = dec(my_sum)  # 传参

print(my_sum (1,2,3,4,5)）
print(my_sum (1,2,3,4,5,'6')）
# my_sum就是in_dec函数，会先执行参数类型判断，然后执行__closure__中的函数my_sum

def dec(func):
  def in_dec(*arg): # my_sum
    print ('in dec arg= ',arg)
    if len(arg) ==0:
      return 0
    for val in arg:
      if not isinstance(val, int):
        return 0
    return func(*arg)  # 闭包，存在于in_dec函数中的__closure__中，所以可以调用
  return in_dec  # 如果没有返回值，则my_sum调用装饰器后为None

# my_sum = dec(my_sum)  # 不手动传参
@dec     # 装饰器将my_sum作为参数传入dec，并返回一个新的函数赋值给my_sum
def my_sum(*arg):
  return sum(arg)
def my_average(*arg):
  return sum(arg)/len(arg)

print(my_sum (1,2,3,4,5))
print(my_sum (1,2,3,4,5,'6'))

def deco(func):
  def in_deco(x,y):
    print ('in deco')
    func(x,y)
  print ('call deco')
  return in_deco

@deco
def bar(x, y):
  print ('in bar',x+y)

bar(1,2)