1、开放封闭原则：对扩展开放、对修改是封闭
2、装饰器：装饰它人的，器指的是任意可调用对象，现在的场景装饰器（函数）
被装饰的对象也是函数
原则：1、不修改装饰对象的源代码；2、不修改被装饰对象的调用方式
装饰器的目的：在遵循1,2的前提下为被装饰对象添加上新功能
一、无参装饰器
import time
def timmer(func):
def inner():
start = time.time()
func()
end = time.time()
print("run time is %s" %(end - start))
return inner
@timmer #相当于index = timmer(index)
def index():
time.sleep(3)
print("welcome to index")
index() #相当于inner()
输出结果：welcome to index
run time is 3.0010766983032227
改进一：
import time
def timmer(func):
def inner():
start = time.time()
res = func()
end = time.time()
print("run time is %s" %(end - start))
return res
return inner
@timmer 相当于index = timmer(index)
def index():
time.sleep(3)
print("welcome to index")
return 1111
res = index() #相当于res = inner()
print(res)
输出结果：welcome to index
run time is 3.0010766983032227
1111
改进二：
import time
def timmer(func):
def inner(*args,**kwargs):
start = time.time()
res = func(*args,**kwargs)
end = time.time()
print("run time is %s" %(end - start))
return res
return inner
@timmer #相当于index = timmer(index)
def index(name):
time.sleep(3)
print("welcome %s to index" %name)
return 1111
res = index('keke') #相当于res = inner('keke')
print(res)
输出结果：welcome keke to index
run time is 3.000697135925293
1111
二、有参装饰器
import time
def outter(file):
def welcome(func):
def inner():
name = input("name>>:").strip()
res = func(name)
if file == 'mysql':
print("mysql")
elif file == 'mangodb':
print('mangodb')
else:
print('others!!!')
return res
return inner
return welcome
@outter(file='mangodb') 相当于@welcome index=welcome(index)
def index(name):
time.sleep(3)
print('welcome %s to index' %name)
return 1111
res = index()
print(res)
输出结果：name>>:keke
welcome keke to index
mangodb
1111
