Python 装饰器原理、定义与用法详解

def sayHi(name="hjj2"):
 print 'inside sayHi() func'
 def greet():
  return 'inside greet() func'
 print(greet())
sayHi()
#output
#  inside sayHi() func
#  inside greet() func

def sayHi():
 return 'hi hjj2'
def doSthBeforeSayHi(func):
 print 'before sayHi func'
 print(func())
doSthBeforeSayHi(sayHi)
#output
#  before sayHi func
#  hi hjj2

def new_decorator(func):
  def wrapDecorator():
   print 'before func'
   func()
   print 'after func'
  return wrapDecorator
def func_require_decorator():
  print 'a func need decorator'
func_require_decorator()
#ouput: a func need decorator
func_require_decorator = new_decorator(func_require_decorator)
func_require_decorator()
#ouput:
#  before func
#  a func need decorator
#  after func

@new_decorator
func_require_decorator()
#ouput:
#  before func
#  a func need decorator
#  after func

func_require_decorator = new_decorator(func_require_decorator)

from functools import wraps
def new_decorator(func):
  @wraps(func)
  def wrapDecorator():
   print 'before func'
   func()
   print 'after func'
  return wrapDecorator
def func_require_decorator():
  print 'a func need decorator'
@new_decorator
func_require_decorator()
print(func_require_decorator.__name__)
#ouput: func_require_decorator

from functools import wraps
def requires_auth(f):
  @wraps(f)
  def decorated(*args, **kwargs):
    auth = request.authorization
    if not auth or not check_auth(auth.username, auth.password):
      authenticate()
    return f(*args, **kwargs)
  return decorated

from functools import wraps
def logit(logfile='out.log'):
  def logging_decorator(func):
    @wraps(func)
    def wrapped_function(*args,**kwargs):
      log_string = func.__name__+"was called"
      print(log_string)
      with open(logfile,'a') as opened_file:
        opened_file.write(log_string+'\n')
      return func(*args,**kwargs)
    return wrapped_function
  return logging_decorator
@logit()
def func1():
  pass
func1()

from functools import wraps
class logit(object):
  def __init__(self, logfile='out.log'):
    self.logfile = logfile
  def __call__(self, func):
    @wraps(func)
    def wrapped_function(*args, **kwargs):
      log_string = func.__name__ + "was called"
      print(log_string)
      # 打开logfile并写入
      with open(self.logfile, 'a') as open_file:
        # 将日志写到指定文件
        open_file.write(log_string + '\n')
      # 发送一个通知
      self.notify()
      return func(*args, **kwargs)
    return wrapped_function
  def notify(self):
    pass
@logit()
def myfunc1():
  pass
class email_logit(logit):
  '''
  实现在函数调用时发送email
  '''
  def __init__(self, email='admin@xxx.com', *args, **kwargs):
    self.email = email
    super(email_logit, self).__init__(*args, **kwargs)
  def notify(self):
    '''
    发送邮件通知
    '''
    pass