如何立即运行生成器函数的初始化代码，而不是在第一次调用时? [英] How can I run the initialization code for a generator function immediately, rather than at the first call?

问题描述

我有一个类似这样的生成器函数:

I have a generator function that goes something like this:

def mygenerator():
    next_value = compute_first_value() # Costly operation
    while next_value != terminating_value:
        yield next_value
        next_value = compute_next_value()

我希望在调用函数后立即运行初始化步骤(在 while 循环之前)，而不是仅在第一次使用生成器时运行.有什么好的方法可以做到这一点?

I would like the initialization step (before the while loop) to run as soon as the function is called, rather than only when the generator is first used. What is a good way to do this?

我想这样做是因为生成器将在单独的线程(或进程，或任何多处理使用)中运行，并且我不会在短时间内使用 return，而且初始化有点昂贵，所以我希望它在我准备使用这些值时进行初始化.

I want to do this because the generator will be running in a separate thread (or process, or whatever multiprocessing uses) and I won't be using the return for a short while, and the initialization is somewhat costly, so I would like it to do the initialization while I'm getting ready to use the values.

推荐答案

class mygenerator(object):
    def __init__(self):
        next_value = compute_first_value()
    def __iter__(self):
        return self
    def next(self):
        if next_value == terminating_value:
            raise StopIteration()
        return next_value

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