装饰器加载顺序从下至上 执行顺序从上至下
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多层装饰器
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def deco1(func): #func=deco2 def wrapper1(*args, **kwargs): '''this is wrapper1''' print('start 1') result = func(*args, **kwargs)# wrapper2() print('end 1') return result return wrapper1def deco2(func):#func=deco1 def wrapper2(*args, **kwargs): '''this is wrapper2''' print('start 2') result = func(*args, **kwargs)# wrapper3() print('end 2') return result return wrapper2def deco3(func):#func=foo def wrapper3(*args, **kwargs): '''this is wrapper3''' print('start 3') result = func(*args, **kwargs)#wrapper1() print('end 3') return result return wrapper3@deco1##deco1(deco2(deco3(foo)))@deco2 #deco2(deco3(foo))@deco3 #deco3(foo)def foo(x, y): '''this is foo''' return x * yprint(foo(8, 9))#wrapper1(wrapper2( wrapper3(foo)))执行从外往内'''输出结果： start 1 start 2 start 3 end 3 end 2 end 1 72''''''装饰的过程： wrapper3 = deco3(foo) wrapper2 = deco2(wrapper3) wrapper1 = deco1(wrapper2) foo = wrapper1执行的过程：正好和装饰的过程相反。 foo(8, 9)--->wrapper1(8, 9)--->deco1(wrapper2)(8, 9)---> | v deco1( deco2( deco3(foo) ) )(8, 9)<---deco1( deco2(wrapper3) )(8, 9) 类比穿衣服，穿(装饰)的时候从里往外一层套一层，脱(执行)的时候从外到里一层一层脱。'''
