二十四种场景全方位解读Python装饰器的用法

文章目录

• ​​一、 装饰器是函数​​

• ​​1.1 被装饰对象也是函数​​

• ​​1.1.1 装饰器无参数，被装饰对象无参数​​
• ​​1.1.2 装饰器无参数，被装饰对象有参数​​
• ​​1.1.3 装饰器有参数，被装饰对象无参数​​
• ​​1.1.4 装饰器有参数，被装饰器对象有参数​​

• ​​1.2 被装饰器对象是类​​

• ​​1.2.1 装饰器无参数，被装饰类无参数​​
• ​​1.2.2 装饰器无参数，被装饰类有参数​​
• ​​1.2.3 装饰器有参数，被装饰类无参数​​
• ​​1.2.4 装饰器有参数，被装饰类有参数​​

• ​​1.3 被装饰对象是类中的方法​​

• ​​1.3.1 装饰器无参数，被装饰类中的方法无参数​​
• ​​1.3.2 装饰器无参数，被装饰类中的方法有参数​​
• ​​1.3.3 装饰器有参数，被装饰类中的方法无参数​​
• ​​1.2.4 装饰器有参数，被装饰类中的方法有参数​​

• ​​二、 装饰器是类​​

• ​​2.1 被装饰对象是函数​​

• ​​2.1.1 装饰器无参数，被装饰对象无参数​​
• ​​2.1.2 装饰器无参数，被装饰对象有参数​​
• ​​2.1.3 装饰器有参数，被装饰对象无参数​​
• ​​2.1.4 装饰器有参数，被装饰器对象有参数​​

• ​​2.2 被装饰器对象是类​​

• ​​2.2.1 装饰器无参数，被装饰类无参数​​
• ​​2.2.2 装饰器无参数，被装饰类有参数​​
• ​​2.2.3 装饰器有参数，被装饰类无参数​​
• ​​2.2.4 装饰器有参数，被装饰类有参数​​

• ​​2.3 被装饰对象是类中的方法​​

• ​​2.3.1 装饰器无参数，被装饰类中的方法无参数​​
• ​​2.3.2 装饰器无参数，被装饰类中的方法有参数​​
• ​​2.3.3 装饰器有参数，被装饰类中的方法无参数​​
• ​​2.3.4 装饰器有参数，被装饰类中的方法有参数​​

一、 装饰器是函数

1.1 被装饰对象也是函数

装饰器是函数，被装饰对象是函数时，此时装饰器的作用是给被装饰对象的函数做功能增强功能，思想是面向切面编程思想，即在被装饰对象的函数的之前和之后做一些额外处理，而不破坏被装饰函数原有的功能实现，主要有以下几种情况：

1.1.1 装饰器无参数，被装饰对象无参数

def decorator(func):
def _decorator():
print("before func......")
func()
print("after func......")
return _decorator

@decorator
def func():
print("in func()......")

if __name__=="__main__":
func()

执行结果为：

before func......
in func()......
after func......

1.1.2 装饰器无参数，被装饰对象有参数

def decorator(func):
def _decorator(*args,**kwargs):
print("before {name}......".format(name=func.__name__))
func(*args,**kwargs)
print("after {name}......".format(name=func.__name__))
return _decorator

@decorator
def func1():
print("in func1()......")

@decorator
def func2(a,b):
print("in func2()......")
print("a={a},b={b}".format(a=a,b=b))

@decorator
def func3(a,b,c=10):
print("in func3()......")
print("a={a},b={b}".format(a=a, b=b))
print("c={c}".format(c=c))

if __name__=="__main__":
func1()
func2(1,2)
func3(1,2,c=100)

运行结果为：

before func1......
in func1()......
after func1......
before func2......
in func2()......
a=1,b=2
after func2......
before func3......
in func3()......
a=1,b=2
c=100
after func3......

1.1.3 装饰器有参数，被装饰对象无参数

def wrapper(name):
def decorator(func):
def _decorator():
print("before {name} ,decorator param is {param}".format(name=func.__name__,param=name))
print("before {name}......".format(name=func.__name__))
func()
print("after {name}......".format(name=func.__name__))
return _decorator
return decorator

@wrapper(name="hello world")
def func1():
print("in func1()......")

if __name__=="__main__":
func1()

运行结果为：

before func1 ,decorator param is hello world
before func1......
in func1()......
after func1......

1.1.4 装饰器有参数，被装饰器对象有参数

def wrapper(name):
def decorator(func):
def _decorator(*args,**kwargs):
print("before {name} ,decorator param is {param}".format(name=func.__name__,param=name))
print("before {name}......".format(name=func.__name__))
func(*args,**kwargs)
print("after {name}......".format(name=func.__name__))
return _decorator
return decorator

@wrapper(name="hello world")
def func1():
print("in func1()......")

@wrapper(name="hello world")
def func2(a, b):
print("in func2()......")
print("a={a},b={b}".format(a=a, b=b))

@wrapper(name="hello world")
def func3(a, b, c=10):
print("in func3()......")
print("a={a},b={b}".format(a=a, b=b))
print("c={c}".format(c=c))


if __name__=="__main__":
func1()
func2(1,2)
func3(1,2,c=100)

运行结果如下：

before func1 ,decorator param is hello world
before func1......
in func1()......
after func1......
before func2 ,decorator param is hello world
before func2......
in func2()......
a=1,b=2
after func2......
before func3 ,decorator param is hello world
before func3......
in func3()......
a=1,b=2
c=100
after func3......

1.2 被装饰器对象是类

被装饰器对象为类时，装饰器的作用是类在初始化的时候做功能增强，即可以在类初始化之前或者之后做一些功能增强，所以下面所说的被装饰对象有无参数是针对类的初始化函数__init__有无参数而言的，主要有以下几种情况：

1.2.1 装饰器无参数，被装饰类无参数

def decorator(cls):
def _decorator():
print("before class {name} init......".format(name=cls.__name__))
obj=cls()
print("after class {name} init......".format(name=cls.__name__))
return obj
return _decorator

@decorator
class Test(object):
def __init__(self):
print("in class {name} init function......".format(name=Test.__name__))

def func(self):
print("in class {name} func()".format(name=Test.__name__))


if __name__=="__main__":
test=Test()

test.func()

运行结果如下：

before class Test init......
in class _decorator init function......
after class Test init......
in class _decorator func()

1.2.2 装饰器无参数，被装饰类有参数

def decorator(cls):
def _decorator(*args,**kwargs):
print("before class {name} init......".format(name=cls.__name__))
obj=cls(*args,**kwargs)
print("after class {name} init......".format(name=cls.__name__))
return obj
return _decorator

@decorator
class Test(object):
def __init__(self,a,b=10):
print("in class {name} init function......".format(name=Test.__name__))
print("a={a},b={b}".format(a=a,b=b))

def func(self):
print("in class {name} func()".format(name=Test.__name__))


if __name__=="__main__":
test=Test(2,20)

test.func()

执行结果如下：

before class Test init......
in class _decorator init function......
a=2,b=20
after class Test init......
in class _decorator func()

1.2.3 装饰器有参数，被装饰类无参数

def wrapper(name="hello world"):
def decorator(cls):
def _decorator():
print("before class {name} init......".format(name=cls.__name__))
obj=cls()
print("after class {name} init......".format(name=cls.__name__))
return obj
return _decorator
return decorator

@wrapper("hello world")
class Test(object):
def __init__(self):
print("in class {name} init function......".format(name=Test.__name__))

def func(self):
print("in class {name} func()".format(name=Test.__name__))


if __name__=="__main__":
test=Test()

test.func()

执行结果如下：

before class Test init......
in class _decorator init function......
after class Test init......
in class _decorator func()

1.2.4 装饰器有参数，被装饰类有参数

def wrapper(name="hello world"):
def decorator(cls):
def _decorator(*args,**kwargs):
print("before class {name} init......".format(name=cls.__name__))
obj=cls(*args,**kwargs)
print("after class {name} init......".format(name=cls.__name__))
return obj
return _decorator
return decorator

@wrapper("hello world")
class Test(object):
def __init__(self,a,b=10):
print("in class {name} init function......".format(name=Test.__name__))
print("a= {a} b={b}".format(a=a,b=b))

def func(self):
print("in class {name} func()".format(name=Test.__name__))


if __name__=="__main__":
test=Test(2,b=20)

test.func()

运行结果如下：

before class Test init......
in class _decorator init function......
a= 2 b=20
after class Test init......
in class _decorator func()

1.3 被装饰对象是类中的方法

当被装饰对象是类中的方法时，装饰器的作用是对类中的方法进行功能加强，此时需要注意的是装饰器的内层函数需要增加一个self形参

1.3.1 装饰器无参数，被装饰类中的方法无参数

def decorator(func):
def _decorator(self):
print("before method {name}......".format(name=func.__name__))
obj = func(self)
print("after method {name} ......".format(name=func.__name__))
return obj

return _decorator


class Test(object):
def __init__(self, a=1, b=10):
self.a = a
self.b = b

@decorator
def func(self):
print("in class {name} func()".format(name=Test.__name__))
print("a={a} b={b}".format(a=self.a, b=self.b))


if __name__ == "__main__":
test = Test()

test.func()

执行结果如下：

before method func......
in class Test func()
a=1 b=10
after method func ......

1.3.2 装饰器无参数，被装饰类中的方法有参数

(func):
def _decorator(self,*args,**kwargs):
print("before method {name} ......".format(name=func.__name__))
obj=func(self,*args,**kwargs)
print("after method {name} ......".format(name=func.__name__))
return obj
return _decorator

class Test(object):
def __init__(self,a=1,b=10):
self.a=a
self.b=b
@decorator
def func(self,c,d=20):
print("in class {name} func()".format(name=Test.__name__))
print("a={a} b={b}".format(a=self.a,b=self.b))
print("c={c} d={d}".format(c=c,d=d))

if __name__=="__main__":
test=Test()

test.func(2,d=20)

执行结果如下：

before method func ......
in class Test func()
a=1 b=10
c=2 d=20
after method func ......

1.3.3 装饰器有参数，被装饰类中的方法无参数

def wrapper(name="hello world"):
def decorator(func):
def _decorator(self):
print("before method {name} ......".format(name=func.__name__))
print("name = {name}".format(name=name))
obj=func(self)
print("after method {name} ......".format(name=func.__name__))
return obj
return _decorator
return decorator

class Test(object):
def __init__(self,a=1,b=10):
self.a=a
self.b=b
@wrapper(name="Test.func")
def func(self):
print("in class {name} func()".format(name=Test.__name__))
print("a={a} b={b}".format(a=self.a,b=self.b))

if __name__=="__main__":
test=Test()

test.func()

执行结果如下：

before method func ......
name = Test.func
in class Test func()
a=1 b=10
after method func ......

1.2.4 装饰器有参数，被装饰类中的方法有参数

def wrapper(name="hello world"):
def decorator(func):
def _decorator(self,*args,**kwargs):
print("before metthod {name} ......".format(name=func.__name__))
print("name = {name}".format(name=name))
obj=func(self,*args,**kwargs)
print("after method {name} ......".format(name=func.__name__))
return obj
return _decorator
return decorator

class Test(object):
def __init__(self,a=1,b=10):
self.a=a
self.b=b
@wrapper(name="Test.func")
def func(self,c,d=20):
print("in class {name} func()".format(name=Test.__name__))
print("a={a} b={b}".format(a=self.a,b=self.b))
print("c={c} d={d}".format(c=c,d=d))

if __name__=="__main__":
test=Test()

test.func(2,d=20)

执行结果如下：

before metthod func ......
name = Test.func
in class Test func()
a=1 b=10
c=2 d=20
after method func ......

二、 装饰器是类

2.1 被装饰对象是函数

装饰器是类，被装饰对象是函数的时候，是通过装饰器类初始化的时候将被装饰对象函数传递给装饰器类，然后通过自动调用装饰器类中的__call__函数实现对被装饰对象的前后处理，即在这种情况下，只需要在__call__函数中编写在调用被装饰对象前后进行操作的代码即可

2.1.1 装饰器无参数，被装饰对象无参数

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

def __call__(self):
print("before func {func}()...".format(func=self.func.__name__))
result=self.func()
print("after func {func}()...".format(func=self.func.__name__))
return result

@decorator
def func():
print("in func func()...")

if __name__=="__main__":
func()

执行结果如下：

before func func()...
in func func()...
after func func()...

2.1.2 装饰器无参数，被装饰对象有参数

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

def __call__(self,*args,**kwargs):
print("before func {func}()...".format(func=self.func.__name__))
result=self.func(*args,**kwargs)
print("after func {func}()...".format(func=self.func.__name__))
return result

@decorator
def func(a,b=10):
print("in func func()...")
print("a= {a} b={b}".format(a=a,b=b))


if __name__=="__main__":
func(2,b=20)

执行结果如下：

before func func()...
in func func()...
a= 2 b=20
after func func()...

2.1.3 装饰器有参数，被装饰对象无参数

(object):
def __init__(self,name="hello world"):
self.name=name

def __call__(self,func):
def wrapper():
print("before func {func}()...".format(func=func.__name__))
print("name= {name}".format(name=self.name))
result=func()
print("after func {func}()...".format(func=func.__name__))
return result
return wrapper

@decorator()
def func1():
print("in func func2()...")

@decorator("func2_decorator")
def func2():
print("in func func2()...")

@decorator(name="func3_decorator")
def func3():
print("in func func3()...")


if __name__=="__main__":
func1()

func2()

func3()

执行结果如下：

before func func1()...
name= hello world
in func func2()...
after func func1()...
before func func2()...
name= func2_decorator
in func func2()...
after func func2()...
before func func3()...
name= func3_decorator
in func func3()...
after func func3()...

2.1.4 装饰器有参数，被装饰器对象有参数

(object):
def __init__(self,name="hello world"):
self.name=name

def __call__(self,func):
def wrapper(*args,**kwargs):
print("before func {func}()...".format(func=func.__name__))
print("name= {name}".format(name=self.name))
result=func(*args,**kwargs)
print("after func {func}()...".format(func=func.__name__))
return result
return wrapper

@decorator()
def func1():
print("in func func2()...")

@decorator("func2_decorator")
def func2(a):
print("in func func2()...")
print("a={a}".format(a=a))

@decorator(name="func3_decorator")
def func3(a,b=10):
print("in func func3()...")
print("a={a}, b= {b}".format(a=a,b=b))


if __name__=="__main__":
func1()

func2(10)

func3(2,b=20)

执行结果如下：

before func func1()...
name= hello world
in func func2()...
after func func1()...
before func func2()...
name= func2_decorator
in func func2()...
a=10
after func func2()...
before func func3()...
name= func3_decorator
in func func3()...
a=2, b= 20
after func func3()...

2.2 被装饰器对象是类

同样，当被装饰对象是类是，装饰器的作用是对被装饰类的初始化方法进行功能加强，而装饰器则是以类的形式定义的

2.2.1 装饰器无参数，被装饰类无参数

class decorator(object):
def __init__(self,cls):
self.cls=cls

def __call__(self):
print("before init clsss {cls}...".format(cls=self.cls.__name__))
obj=self.cls()
print("after init class {cls}...".format(cls=self.cls.__name__))
return obj

@decorator
class Test():
def __init__(self):
print("in Test class __init__ func...")

def test(self):
print("in Test class test func...")


if __name__=="__main__":
t=Test()
t.test()

执行结果如下：

before init clsss Test...
in Test class __init__ func...
after init class Test...
in Test class test func...

2.2.2 装饰器无参数，被装饰类有参数

class decorator(object):
def __init__(self,cls):
self.cls=cls

def __call__(self,*args,**kwargs):
print("before init clsss {cls}...".format(cls=self.cls.__name__))
obj=self.cls(*args,**kwargs)
print("after init class {cls}...".format(cls=self.cls.__name__))
return obj

@decorator
class Test():
def __init__(self,a,b=10):
print("in Test class __init__ func...")
print("a={a} b={b}".format(a=a,b=b))

def test(self):
print("in Test class test func...")


if __name__=="__main__":
t=Test(2,b=20)
t.test()

执行结果如下：

before init clsss Test...
in Test class __init__ func...
a=2 b=20
after init class Test...
in Test class test func...

2.2.3 装饰器有参数，被装饰类无参数

class decorator(object):
def __init__(self,name="hello world"):
self.name=name

def __call__(self,cls):
def wrapper():
print("before init class {cls}....".format(cls=cls.__name__))
obj=cls()
print("after init class {cls}...".format(cls=cls.__name__))
return obj
return wrapper

@decorator(name="Test Class")
class Test():
def __init__(self):
print("in Test class __init__ func...")

def test(self):
print("in Test class test func...")


if __name__=="__main__":
t=Test()
t.test()

执行结果如下：

before init class Test....
in Test class __init__ func...
after init class Test...
in Test class test func...

2.2.4 装饰器有参数，被装饰类有参数

class decorator(object):
def __init__(self,name="hello world"):
self.name=name

def __call__(self,cls):
def wrapper(*args,**kwargs):
print("before init class {cls}....".format(cls=cls.__name__))
obj=cls(*args,**kwargs)
print("after init class {cls}...".format(cls=cls.__name__))
return obj
return wrapper

@decorator(name="Test Class")
class Test():
def __init__(self,a,b=10):
print("in Test class __init__ func...")
print("a={a}, b={b}".format(a=a,b=b))

def test(self):
print("in Test class test func...")


if __name__=="__main__":
t=Test(2,b=20)
t.test()

执行结果如下：

before init class Test....
in Test class __init__ func...
a=2, b=20
after init class Test...
in Test class test func...

2.3 被装饰对象是类中的方法

2.3.1 装饰器无参数，被装饰类中的方法无参数

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

def __call__(self):
print("before func {func}...".format(func=self.func.__name__))
results=self.func(self)
print("after func {func}...".format(func=self.func.__name__))
return results

class Test():
def __init__(self):
print("in Test class __init__ func...")

@decorator
def test(self):
print("in Test class test func...")


if __name__=="__main__":
t=Test()
t.test()

执行结果如下：

in Test class __init__ func...
before func test...
in Test class test func...
after func test...

2.3.2 装饰器无参数，被装饰类中的方法有参数

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

def __call__(self,*args,**kwargs):
print("before func {func}...".format(func=self.func.__name__))
results=self.func(self,*args,**kwargs)
print("after func {func}...".format(func=self.func.__name__))
return results

class Test():
def __init__(self):
print("in Test class __init__ func...")

@decorator
def test(self,a,b=10):
print("in Test class test func...")
print("a={a} b={b}".format(a=a,b=b))


if __name__=="__main__":
t=Test()
t.test(2,b=20)

执行结果如下：

in Test class __init__ func...
before func test...
in Test class test func...
a=2 b=20
after func test...

2.3.3 装饰器有参数，被装饰类中的方法无参数

class decorator(object):
def __init__(self,name="hello world"):
self.name=name

def __call__(self,func):
def wrapper(self):
print("before func {func}...".format(func=func.__name__))
results=func(self)
print("after func {func}...".format(func=func.__name__))
return results
return wrapper

class Test():
def __init__(self):
print("in Test class __init__ func...")

@decorator(name="Test_test")
def test(self):
print("in Test class test func...")

if __name__=="__main__":
t=Test()
t.test()

执行结果如下：

in Test class __init__ func...
before func test...
in Test class test func...
after func test...

2.3.4 装饰器有参数，被装饰类中的方法有参数

class decorator(object):
def __init__(self,name="hello world"):
self.name=name

def __call__(self,func):
def wrapper(self,*args,**kwargs):
print("before func {func}...".format(func=func.__name__))
results=func(self,*args,**kwargs)
print("after func {func}...".format(func=func.__name__))
return results
return wrapper

class Test():
def __init__(self):
print("in Test class __init__ func...")

@decorator(name="Test_test")
def test(self,a,b=10):
print("in Test class test func...")
print("a={a}, b={b}".format(a=a,b=b))


if __name__=="__main__":
t=Test()
t.test(2,b=20)

执行结果如下：

in Test class __init__ func...
before func test...
in Test class test func...
a=2, b=20
after func test...