Python 装饰器笔记

一、装饰器无参数

1.原函数无参数

defwrap_in_tag_b(fn):#wrap_in_tag_b是真正的装饰器
defwrapped():
return"<b>"+fn()+"</b>"
returnwrapped

defwrap_in_tag_i(fn):
defwrapped():
return"<i>"+fn()+"</i>"
returnwrapped

@wrap_in_tag_b
@wrap_in_tag_i
defhello():
return"hello"

print(hello())#returns"<b><i>helloworld</i></b>"

2.原函数带参数

defwrap_in_tag_b(fn):
defwrapped(arg):#arg是原函数参数
return"<b>"+fn(arg)+"</b>"
returnwrapped

defwrap_in_tag_i(fn):
defwrapped(arg):#arg是原函数参数
return"<i>"+fn(arg)+"</i>"
returnwrapped

@wrap_in_tag_b
@wrap_in_tag_i
defhello(name):
return"hello{}".formar(name)

print(hello('Jack'))

二、装饰器带参数

1.原函数无参数

defwrap_in_tag(deco_arg):
#装饰器参数：deco_arg
#可以在任意位置使用
defreal_decorator(func):#real_decorator才是即将返回的真正的装饰器
　　　　#原函数参数：func_arg
　　　　#只可以在此位置使用
　　　　defwrapped():
return"<{0}>{1}</{0}>".format(deco_arg,func())
returnwrapped
returnreal_decorator

@wrap_in_tag('b')
@wrap_in_tag('i')
defhello():
return"hello"

print(hello())

2.原函数带参数

defwrap_in_tag(deco_arg):
#装饰器参数：deco_arg
#可以在任意位置使用
defreal_decorator(func):#real_decorator才是即将返回的真正的装饰器
defwrapped(func_arg):
#原函数参数：func_arg
#只可以在此位置使用
return"<{0}>{1}</{0}>".format(deco_arg,func(func_arg))
returnwrapped
returnreal_decorator

@wrap_in_tag('b')
@wrap_in_tag('i')
defhello(name):
return"hello{}".format(name)

print(hello('Jack'))

三、装饰器类

1.原函数无参数

classwrap_in_tag(object):
def__init__(self,deco_arg):
self.tag=deco_arg#装饰器参数：deco_arg

def__call__(self,func):
defnewf():#原函数无参数
return"<{0}>{1}</{0}>".format(self.tag,func())
returnnewf

@wrap_in_tag('b')
@wrap_in_tag('i')
defhello():
return'hello'

print(hello())

2.原函数带参数

classwrap_in_tag(object):
def__init__(self,deco_arg):
self.tag=deco_arg#装饰器参数：deco_arg

def__call__(self,func):
defnewf(func_arg):#原函数参数:func_arg
return"<{0}>{1}</{0}>".format(self.tag,func(func_arg))
returnnewf

@wrap_in_tag('b')
@wrap_in_tag('i')
defhello(name):
return"hello{}".format(name)

print(hello('Jack'))

四、用装饰器装饰类

1.用函数作为装饰器

defwrap_in_tag(deco_arg):
defreal_decorator(func):
defwrapped(self,func_arg):#类方法接收第一个参数都是self，这个必须有，而无论func_arg是否有!!!
return"<{0}>{1}</{0}>".format(deco_arg,func(func_arg))
returnwrapped
returnreal_decorator

classfoo(object):

@wrap_in_tag('b')
@wrap_in_tag('i')
defhello(self,name):
return'hello{}".format(name)

@wrap_in_tag('b')
@wrap_in_tag('i')
defbyebye(self,name):
return'byebye{}".format(name)

f=foo()
print(f.hello('Jack')

2.用类作为装饰器

classwrap_in_tag(object):
def__init__(self,deco_arg):
self.tag=deco_arg

def__call__(self,func):
defnewf(slf,func_arg):#slf必须！self被占用了，那就给第一个参数另一个名字slf（随便）
return"<{0}>{1}</{0}>".format(self.tag,func(func_arg))
returnnewf

classfoo(object):

@wrap_in_tag('b')
@wrap_in_tag('i')
defhello(self,name):
return'hello{}".format(name)

@wrap_in_tag('b')
@wrap_in_tag('i')
defbyebye(self,name):
return'byebye{}".format(name)

f=foo()
print(f.hello('Jack'))