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Python装饰器用法实例分析

yipeiwu_com5年前 (2020-03-06)Python基础

本文实例讲述了Python装饰器用法。分享给大家供大家参考，具体如下：

无参数的装饰器

#coding=utf-8
def log(func):
  def wrapper():
    print 'before calling ',func.__name__
    func()
    print 'end calling ',func.__name__
  return wrapper
@log
def hello():
  print 'hello'
@log
def hello2(name):
  print 'hello',name
if __name__=='__main__':
  hello()

运行结果：

before calling hello
hello
end calling hello

带参数的装饰器:

#coding=utf-8
def log(func):
  def wrapper(name):
    print 'before calling ',func.__name__
    func(name)
    print 'end calling ',func.__name__
  return wrapper
@log
def hello(name):
  print 'hello',name
@log
def hello2(name):
  print 'hello',name
if __name__=='__main__':
  hello('haha')

运行结果：

before calling hello
hello haha
end calling hello

多个参数的时候:

#coding=utf-8
def log(func):
  '''
  *无名字的参数
  **有名字的参数
  :param func:
  :return:
  '''
  def wrapper(*args,**kvargs):
    print 'before calling ',func.__name__
    print 'args',args,'kvargs',kvargs
    func(*args,**kvargs)
    print 'end calling ',func.__name__
  return wrapper
@log
def hello(name,age):
  print 'hello',name,age
@log
def hello2(name):
  print 'hello',name
if __name__=='__main__':
  hello('haha',2)
  hello(name='hehe',age=3)

输出:

end calling hello
before calling hello
args () kvargs {'age': 3, 'name': 'hehe'}
hello hehe 3
end calling hello

装饰器里带参数的情况

本质就是嵌套函数

#coding=utf-8
def log(level,*args,**kvargs):
  def inner(func):
    def wrapper(*args,**kvargs):
      print level,'before calling ',func.__name__
      print level,'args',args,'kvargs',kvargs
      func(*args,**kvargs)
      print level,'end calling ',func.__name__
    return wrapper
  return inner
@log(level='INFO')
def hello(name,age):
  print 'hello',name,age
@log
def hello2(name):
  print 'hello',name
if __name__=='__main__':
  hello('haha',2)

运行输出：