python 各种装饰器示例（python3）

参考网址：

Python中的各种装饰器详解_python_脚本之家
http://www.jb51.net/article/63892.htm

一、函数式装饰器：

1、装饰器无参数，被装饰对象无参数

 def test(func):
     def _test():    #_test函数内使用或返回func()
         print('call the function {0}.'.format(func.__name__))
         return func()
     return _test

 @test
 def say():
     print('hello,world')

 say()

 输出：
 call the function say.
 hello,world

2、装饰器无参数，被装饰对象有参数

 def test(func):
     def _test(*args,**kw):
         print('call the function {0}.'.format(func.__name__))
         return func(*args,**kw)
     return _test

 @test
 def say(str1,length):
     print(str1[:length])

 say('hello,world',5)

 输出：
 call the function say.
 hello

3、装饰器有参数，被装饰对象无参数

 def  arg_test(str_arg):
     def test(func):
         def _test():
             print('call the function {0}.'.format(func.__name__))
             print(str_arg)
             return func()
         return _test
     return test

 @arg_test('with arg')
 def say():
     print('hello,world')

 say()

 输出：
 call the function say.
 with arg
 hello,world

如果装饰器有默认参数，则用@arg_test()，无参数的装饰器直接用@arg_test

4、装饰器有参数，被装饰对象有参数

 def  arg_test(str_arg):
     def test(func):
         def _test(*args,**kw):
             print('call the function {0}.'.format(func.__name__))
             print(str_arg)
             return func(*args,**kw)
         return _test
     return test

 @arg_test('with arg')
 def say(str1,length):
     print(str1[:length])

 say('hello,world',5)

 输出：
 call the function say.
 with arg
 hello

二、类装饰器

1、装饰器无参数，被装饰对象无参数

 class test(object):
     def __init__(self,func):
         self._func = func

     def __call__(self):
         print('call the function {0}. '.format(self._func.__name__))
         return self._func()

 @test
 def say():
     print ('hello,world')

 @test
 def hehe():
     print('hehe')

 say()
 hehe()

 输出：
 call the function say.
 hello,world
 call the function hehe.
 hehe

2、装饰器无参数，被装饰对象有参数

 class test(object):
     def __init__(self,func):
         self._func = func

     def __call__(self,*args,**kw):
         print('call the function {0}. '.format(self._func.__name__))
         return self._func(*args,**kw)

 @test
 def say(str1,length):
     print (str1[:length])

 say('hello,world',5)

 输出：
 call the function say.
 hello

3、装饰器有参数，被装饰对象无参数

 class test(object):
     def __init__(self,info='de_arg'):
         self._info = info

     def __call__(self,func):
         def __call():
             print (self._info)
             print('call the function {0}. '.format(func.__name__))
             return func()
         return __call

 @test()
 def say():
     print ('hello,world')

 say()

 输出：
20 de_arg
21 call the function say. 
22 hello,world

3、装饰器有参数，被装饰对象有参数

 class test(object):
     def __init__(self,info='de_arg'):
         self._info = info

     def __call__(self,func):
         def __call(*args,**kw):
             print (self._info)
             print('call the function {0}. '.format(func.__name__))
             return func(*args,**kw)
         return __call

 @test()
 def say(str1,length):
     print (str1[:length])

 say('hello,world',5)

 输出：
 de_arg
 call the function say.
 hello

三、防止装饰器修改函数名  __name_-

 # import functools

 def  arg_test(str_arg):
     def test(func):
         # @functools.wraps(func)
         def _test():
             print('call the function {0}.'.format(func.__name__))
             print(str_arg)
             return func()
         return _test
     return test

 @arg_test('with arg')
 def say():
     print (say.__name__)
     print('hello,world')

 say()

 输出：
 call the function say.
 with arg
 _test      #函数名被修改
 hello,world

使用functools包

 1 import functools

 def  arg_test(str_arg):
     def test(func):
 5         @functools.wraps(func)
         def _test():
             print('call the function {0}.'.format(func.__name__))
             print(str_arg)
             return func()
         return _test
     return test

 @arg_test('with arg')
 def say():
     print (say.__name__)
     print('hello,world')

 say()

 输出：
 call the function say.
 with arg
 say              #函数名不变
 hello,world