python 装饰器
装饰器
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2* 可以包装函数,类的"函数"
* 装饰器本质 接收一个函数对象(可调用对象),返回一个可调用对象(返回的是在装饰器中定义的函数)包装函数的装饰器
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//示例2:
[root@dev test]# cat decol2.py
#!/usr/bin/env python
# coding: utf-8
def deco(F): # 定义装饰器,装饰器是特殊的函数. F表示可调用对象
def new_F(a,b): # 定义一个新的函数
print("input",a,b) # 打印a和b
return F(a,b) # 返回传入"函数可调用对象",并将a和b,传入到可调用对象
return new_F # 返回这个定义的函数对象,类似闭包
# 计算平方和
@deco # 采用装饰器,在函数定义之前
def square_sum(a,b):
return a**2 + b**2
# 计算平方差
@deco
def square_diff(a,b):
return a**2 - b**2
print(square_sum(3,4))
print(square_diff(3,4))
[root@dev test]# python decol2.py
('input', 3, 4)
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('input', 3, 4)
-7
示例3:
[root@dev test]# cat decol3.py
#!/usr/bin/env python
# coding: utf-8
# 新的装饰器
def pre_str(pre=''):
# 旧的装饰器
def decorator(F):
def new_F(a,b):
print(pre + 'input' ,a,b)
return F(a,b)
return new_F
return decorator
# 计算平方和
@pre_str(pre='hi + ')
def square_sum(a,b):
return a**2 + b**2
# 计算平方差
@pre_str(pre='hi - ')
def square_diff(a,b):
return a**2 - b**2
print(square_sum(3,4))
print(square_diff(3,4))
[root@dev test]# python decol3.py
('hi + input', 3, 4)
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('hi + input', 3, 4)
-7包装类的装饰器
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32[root@dev test]# cat decol4.py
#!/usr/bin/env python
# coding: utf-8
def decorator(aClass):
class newClass:
def __init__(self,age):
self.total_display = 0
self.wrapped = aClass(age)
def disply(self):
self.total_display += 1
print("total display",self.total_display)
self.wrapped.display()
return newClass
@decorator
class Bird:
def __init__(self,age):
self.age = age
def display(self):
print('My age is ',self.age)
a = Bird(5)
for i in range(3):
a.disply()
[root@dev test]# python decol4.py
('total display', 1)
('My age is ', 5)
('total display', 2)
('My age is ', 5)
('total display', 3)
('My age is ', 5)