#开放封闭原则：对修改封闭，对扩展开放
装饰器他人的器具，本身可以是任意可调用对象，被装饰者也可以是任意可调用对象。 强调装饰器的原则：1 不修改被装饰对象的源代码 2 不修改被装饰对象的调用方式 装饰器的目标：在遵循1和2的前提下，为被装饰对象添加上新功能
import time def index(): time.sleep(3) print(‘welcome to index‘) # index() def wrapper(func): start_time = time.time() func() stop_time = time.time() print(‘run time is %s‘ % (stop_time - start_time)) wrapper(index) # ================闭包实现============================= import time def index(): time.sleep(3) print(‘welcome to index‘) def timmer(): func = index # 这么写严格收到层级限制了，内部的函数无法调取，需要return返回值 def wrapper(): # 注意这里，func已经定义了等于index，就不需要写默认参数了 start_time = time.time() func() stop_time = time.time() print(‘run time is %s‘ % (stop_time - start_time)) return wrapper # wrapper=timmer() #运行timmer，得到的结果是wrapper，并且把值赋给了wrapper # wrapper() index = timmer() # 如上，既然可以把timmer运行的返回值赋值给warpper，那么同理也可以赋值给index index() ####这么写没有修改源代码，也没有修改调用方式，也加上的新功能。实现了装饰器 ####这么写其实是有问题的，如果又来了一个函数。这种闭包就无法实现了。解决方法如下 # ============================================== import time def index(): time.sleep(3) print(‘welcome to index‘) def home(): time.sleep(2) print(‘welcome to home page‘) # index() def timmer(func): # func=index def wrapper(): # 注意这里，func已经定义了等于index，就不需要写默认参数了 start_time = time.time() func() stop_time = time.time() print(‘run time is %s‘ % (stop_time - start_time)) return wrapper index = timmer(index) # 给func一个index的值，最后返回的值是wrapper，我可以把它赋值给index,home同理 home = timmer(home) index() home() # =================装饰器======================= import time def timmer(func): # func=index def wrapper(): start = time.time() func() stop = time.time() print(‘run time is %s‘ % (stop - start)) return wrapper @timmer # index=timmer(index) 自上而下运行，代表调用timmer 并且给timmer传值为index def index(): time.sleep(3) print(‘welcome to index‘) @timmer # home=timmer(home) def home(): time.sleep(2) print(‘welcome to home page‘) index() home() # =================被装饰器是有参函数======================= import time def timmer(func): # func=index def wrapper(name): start = time.time() func(name) stop = time.time() print(‘run time is %s‘ % (stop - start)) return wrapper @timmer # home=timmer(home) def home(name): time.sleep(2) print(‘welcome %s home ‘ % (home)) home(‘egon‘) # ===========有参和无参混合用======================= import time def timmer(func): # func=index def wrapper(*args, **kwargs): # 闭包函数适应有参无参，各种* 传参的方式 start = time.time() func(*args, **kwargs) stop = time.time() print(‘run time is %s‘ % (stop - start)) return wrapper @timmer # index=timmer(index) 自上而下运行，代表调用timmer 并且给timmer传值为index def index(): time.sleep(3) print(‘welcome to index‘) @timmer # home=timmer(home) def home(name): time.sleep(2) print(‘welcome %s to home ‘ % (name)) index() home(‘agon‘)
import time def timmer(func): def wrapper(*args, **kwargs): start = time.time() res = func(*args, **kwargs) stop = time.time() print(‘run time is %s‘ % (stop - start)) return res return wrapper @timmer # index=timmer(index) def index(): time.sleep(3) print(‘welcome to index‘) return 123 @timmer # home=timmer(home) def home(name): time.sleep(2) print(‘welcome %s to home page‘ % name) # res=index() #res=wrapper() # print(res) res1 = home(‘egon‘) # wrapper(‘egon‘) print(res1)
import time def timmer(func): def wrapper(*args,**kwargs): start_time=time.time() res=func(*args,**kwargs) stop_time=time.time() print(‘run time is %s‘ %(stop_time-start_time)) return res return wrapper @timmer def foo(): time.sleep(3) print(‘from foo‘) foo()
def auth(driver=‘file‘): def auth2(func): def wrapper(*args,**kwargs): name=input("user: ") pwd=input("pwd: ") if driver == ‘file‘: if name == ‘egon‘ and pwd == ‘123‘: print(‘login successful‘) res=func(*args,**kwargs) return res elif driver == ‘ldap‘: print(‘ldap‘) return wrapper return auth2 @auth(driver=‘file‘) def foo(name): print(name) foo(‘egon‘)
被装饰函数的正上方，单独一行
@deco1
@deco2
@deco3
def foo():
pass
foo=deco1(deco2(deco3(foo)))
current_user = {‘user‘: None}
def auth(func):
def wrapper(*args, **kwargs):
if current_user[‘user‘]:
return func(*args, **kwargs)
name = input(‘name: ‘).strip()
password = input(‘password: ‘).strip()
with open(‘db.txt‘, encoding=‘utf-8‘) as f:
user_dic = eval(f.read())
if name in user_dic and password == user_dic[name]:
res = func(*args, **kwargs)
current_user[‘user‘] = name
return res
else:
print(‘user or password error‘)
return wrapper
@auth # index=auth(index) index=wrapper
def index():
print(‘from index‘)
index()
@auth
def home(name):
print(‘welcome %s‘ % name)
index() # wrapper()
home(‘egon‘)
current_user = {‘user‘: None}
def auth(auth_type=‘file‘):
def deco(func):
def wrapper(*args, **kwargs):
if auth_type == ‘file‘:
if current_user[‘user‘]:
return func(*args, **kwargs)
name = input(‘name: ‘).strip()
password = input(‘password: ‘).strip()
with open(‘db.txt‘, encoding=‘utf-8‘) as f:
user_dic = eval(f.read())
if name in user_dic and password == user_dic[name]:
res = func(*args, **kwargs)
current_user[‘user‘] = name
return res
else:
print(‘user or password error‘)
elif auth_type == ‘mysql‘:
print(‘mysql‘)
elif auth_type == ‘ldap‘:
print(‘ldap‘)
else:
print(‘not valid auth_type‘)
return wrapper
return deco
@auth(auth_type=‘mysql‘) # @deco #index=deco(index)
def index():
print(‘from index‘)
@auth(auth_type=‘file‘)
def home(name):
print(‘welcome %s‘ % name)
index() # wrapper()
home(‘egon‘)
from functools import wraps
def deco(func):
@wraps(func) #加在最内层函数正上方
def wrapper(*args,**kwargs):
return func(*args,**kwargs)
return wrapper
@deco
def index():
‘‘‘哈哈哈哈‘‘‘
print(‘from index‘)
print(index.__doc__)
原文：http://www.cnblogs.com/xiechao621/p/8007179.html