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img { max-width: 100% }

python生成器

python生成器基于yield语句，生成器可以暂停函数并返回一个中间结果。该函数会保存执行上下文，稍后必要时可以恢复。

def fibonacci():    a,b=0,1    while True:        yield b        a,b=b,a+bfib=fibonacci() next(fib)#输出的是b，与迭代器的使用相同，用next函数。  #fibonacci()函数返回一个生成器对象，是特殊的迭代器，他知道如何保存执行上下文。他可以被无限次调用，每次都会生成序列的下一个元素。  def power(values):    for value in values:        print("powering %s"%value)        yield valuedef adder(values)    for value in values:        print("adding to %s"%value)        if value%2==0:            yield value+3        else:            yield value+2elements=[1,4,7,9,12,19]results=adder(power(elements))next(results)  

生成器的另一个重要的特性，就是能够利用next函数与调用的代码进行交互，yield变成一个表达式，而值可以通过名为send的新方法传递

def psychologist（）：    print("Please tell me you problem")    while True:        ans=(yield)        if ans is not None:            if ans.endswith(‘?‘):                print("Don‘t ask yourself too much questions")            elif ‘good‘ in ans:                print("ahh that‘s good,go on")            elif ‘bad‘ in ans:                print("Don‘t be so negative")  free=psychologist()next(free)free.send("I feel bad")

send的作用与next类似，但会将函数定义内部的值变成yield的返回值。使用send函数是可以改变根据客户端代码改变自身行为的

原文地址：https://www.cnblogs.com/dcotorbool/p/8158085.html