Python之装饰器
装饰器是由函数去生成的，用于装饰某个函数或者方法或者类，他可以让这个函数在执行之前或者执行之后做一些操作。
实例
先定义一个函数func
#!/usr/bin/env python
# _*_ coding: utf-8 _*_
def func(arg): # 接受一个参数arg
print(arg) # 输出这个参数
func("Hello World!") # 调用脚本并且传入参数
执行脚本，输出的结果为：
C:\Python35\python.exe F:/Python_code/Note/装饰器.py
Hello World!
Process finished with exit code 0
现要在执行func这个函数前后执行一些操作，就可以创建一个装饰器来实现：
#!/usr/bin/env python
# _*_ coding: utf-8 _*_
def decorator(func): # 创建一个装饰器函数，接受的参数arg参数就是func函数名
def inner(*args, **kwargs):
print("执行函数之前")
ret = func(*args, **kwargs)
print("执行函数之后")
return ret
return inner
@decorator # 如果要让某个函数使用装饰器，只需要在这个函数上面加上@+装饰器名
def func(arg):
print(arg)
func("Hello World!")
输出结果为：
/usr/bin/python3.5 /home/ansheng/Documents/PycharmProjects/blogcodes/装饰器.py
执行函数之前
Hello World!
执行函数之后
Process finished with exit code 0
多个装饰器装饰同一个函数
#!/usr/bin/env python
# _*_ coding: utf-8 _*_
def decorator1(func):
def inner():
print("开始之前执行装饰器01")
ret = func()
print("结束之后执行装饰器01")
return ret
return inner
def decorator2(func):
def inner():
print("decorator2>>>Start...")
ret = func()
print("decorator2>>>End...")
return ret
return inner
@decorator1
@decorator2
def index():
print("执行函数...")
index()
输出结果：
/usr/bin/python3.5 /home/ansheng/Documents/PycharmProjects/blogcodes/装饰器.py
开始之前执行装饰器01
decorator2>>>Start...
执行函数...
decorator2>>>End...
结束之后执行装饰器01
Process finished with exit code 0
更多实例
#!/usr/bin/env python
# _*_ coding:utf-8 _*_
# Created by 安生 on 2017/2/9
"""
函数装饰器
"""
def decorator(func):
def wrapped(*args, **kwargs):
return func(*args, **kwargs)
return wrapped
@decorator
def func(a, b):
return a + b
print(func(1, 2))
"""
类装饰器
"""
class decorator:
def __init__(self, func):
self.func = func
def __call__(self, *args, **kwargs):
return self.func(*args, **kwargs)
@decorator
def func(a, b):
return a + b
print(func(1, 2))
"""
带参数的函数装饰器
"""
def parameter(a, b):
print(a, b)
def decorator(func):
def wrapped(*args, **kwargs):
return func(*args, **kwargs)
return wrapped
return decorator
@parameter(1, 2)
def func(a, b):
return a + b
print(func(10, 20))
"""
带参数的类装饰器
"""
def parameter(a, b):
print(a + b)
class decorator:
def __init__(self, func):
self.func = func
def __call__(self, *args, **kwargs):
return self.func(*args, **kwargs)
return decorator
@parameter(1, 2)
def func(a, b):
return a + b
print(func(10, 20))
"""
带参数的类装饰器
"""
def parameter(a, b):
print(a, b)
def decorator(cls):
class wrapped:
def __init__(self, *args, **kwargs):
self.cls = cls(*args, **kwargs)
def __getattr__(self, item):
return getattr(self.cls, item)
return wrapped
return decorator
@parameter(1, 2)
class CLS:
def __init__(self):
self.a = 'a'
def P(self, v):
print(v)
obj = CLS()
print(obj.a)
obj.P('Hello,')
"""
为函数中和类中的方法添加装饰器
"""
def Call(aClass):
calls = 0
def onCall(*args, **kwargs):
nonlocal calls
calls += 1
print('call %s to %s' % (calls, func.__name__))
return aClass(*args, **kwargs)
return onCall
@Call
def func(a, b):
return a + b
print(func(1, 2))
class CLS:
def __init__(self):
self.a = 'a'
@Call
def b(self):
return self.a
obj = CLS()
print(obj.b())
本文出自 “一盏烛光” 博客，谢绝转载！