【Python】-018-函数-装饰器

例子1——无嵌套结构装饰器

##  装饰器在被装修函数前，而且导入时就被执行
# -*- coding: utf-8 -*-
def decoFunc(f):
    print "Before", f.__name__," function called."  #传递函数f，没有参数传入
    return f

def function1():
    print "Fucntion 1 called"

@decoFunc
def fucntion2():
    print "Function 2 called"

if __name__ == "__main__":
    ## pass
    decoFunc(function1)()
    fucntion2()

惰性计算，还没有运行，只是声明

例子2——2层嵌套结构装饰器

import time

def timeInterval(doSomething):
    def nestedFuction(* tuple, **dicts):  #保证参数掺入，用动态参数，一个*表示元组，**表示字典
        startTime = time.clock()
        a = doSomething(*tuple, **dicts)
        print "arguments: ",args, dicts
        endTime = time.clock()
        print doSomething.__name__, "run cost time is ", endTime-startTime
        return a
    return nestedFuction  ##导入时执行，但是仅仅声明函数，并不会影响原有逻辑

@timeInterval
def listComp(length):
    return [(x, y) for x in range(length) for y in       range(length) if x*y>25]

@timeInterval
def forComp(xlen, ylen):
    temp = []
    for i in range(xlen):
        for j in range(ylen):  
            if i*j>25:
                temp.append((i,j))
    return temp

if __name__ == "__main__":
    a = listComp(1000)  ##不改变原有函数调用方式
    b = forComp(1000, 1000)

    print a  #a 是返回值
    print b

更多层级的嵌套，3层嵌套，最外层为装饰器函数本身，其余两层和之前的一致

  #!/usr/bin/env python
  # coding: utf-8

  import time

  def timeInterval(timeF):  ## 装饰器外层函数接受参数timeF，计时函数
      def decorator(doSomething):  ##装饰器接受被装饰函数为参数
          def nestedFuction(*args):  ## 嵌套函数接受被装饰函数的接受参数
              startTime = timeF()
              a = doSomething(*args)
              print "arguments: ",args
              endTime = timeF()
              print doSomething.__name__, "run cost time is ", endTime-startTime
              return a
          return nestedFuction
      return decorator

  @timeInterval(time.clock)
  def listComp(length):
      return [(x, y) for x in range(length) for y in range(length) if x*y>25]

  @timeInterval(time.clock)
  def forComp(xlen, ylen):
      temp = []
      for i in range(xlen):
          for j in range(ylen):  
              if i*j>25:
                  temp.append((i,j))
      return temp

  if __name__ == "__main__":
      a = listComp(1000)
      b = forComp(1000, 1000)