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

问题描述

我有一个生成器函数，其内容如下:

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()

我希望初始化步骤(在while循环之前)在调用函数后立即运行，而不是仅在首次使用生成器时运行.什么是这样做的好方法?

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，或任何多处理使用的线程)中运行，并且我不会在短时间内使用return，并且初始化有些昂贵，所以我我想在准备使用值时进行初始化.

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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