更有条理的调用协程的方式? [英] More organized way to call Coroutines?

问题描述

在我的代码中，我需要在前一个完成后调用多个 Web 请求.例如:

In my code, I have multiple web requests needed to be called after the previous one is finished. For example:

void Init()
{
    StartCoroutine(FirstRequest());
}

IEnumerator FirstRequest()
{
    www = new WWW(my_url);
    yield return www;
    StartCoroutine(SecondRequest());
}

IEnumerator SecondRequest()
{
    www = new WWW(my_url);
    yield return www;
}

如果函数体很大，很容易混淆和凌乱，在Javascript中，有Promise，所以我可以这样做:

If the body of function is huge, it is relly easy to get confusing and messy,in Javascript, there is Promise, so I can do this:

function init() {  
  return validateParams()
    .then(firstRequest)
    .then(SecondRequest)
    .then((result) => {
      console.log(result)
      return result
    })
}

有人知道我应该如何扩展协程才能产生类似的效果吗?

Any one has a clue how should I extend Coroutines so I can have similar effect?

推荐答案

这很简单.只需使用 yield return SecondRequest(); 或 yield return StartCoroutine( SecondRequest()); 即可.协程名称或 StartCoroutine 之前的 yield 应该让它等待该协程返回，然后再继续执行它下面的其他代码.

This is very straightforward. Just use yield return SecondRequest(); or yield return StartCoroutine( SecondRequest());. The yield before the the coroutine name or StartCoroutine should make it wait for that coroutine to return before it continue to execute other code below it.

例如，您有四个应按顺序调用的协程函数:

For example, you have four coroutine functions that should be called sequentially:

IEnumerator FirstRequest()
{
    www = new WWW(my_url);
    yield return www;
}

IEnumerator SecondRequest()
{
    www = new WWW(my_url);
    yield return www;
}

IEnumerator ThirdRequest()
{
    www = new WWW(my_url);
    yield return www;
}

IEnumerator FourthRequest()
{
    www = new WWW(my_url);
    yield return www;
}

然后你可以这样做:

void Init()
{
    StartCoroutine(doSequentialStuff());
}

IEnumerator doSequentialStuff()
{
    //Do first request then wait for it to return
    yield return FirstRequest();

    //Do second request then wait for it to return
    yield return SecondRequest();

    //Do third request then wait for it to return
    yield return ThirdRequest();

    //Do fourth request then wait for it to return
    yield return FourthRequest();
}

<小时>

编辑:

如果我只有成功状态才继续下一个协程怎么办?像 www = new WWW(my_url);收益率返回 www;如果(！www.error)StartCoroutine(SecondRequest());

what if I only proceed to next coroutine if only I got success status? like www = new WWW(my_url); yield return www; if(!www.error) StartCoroutine(SecondRequest());

在这种情况下，您应该使用 Action 作为协程函数中的参数:

In this case, you should use Action as a parameter in the coroutine functions:

IEnumerator FirstRequest(Action<bool> reqStat)
{
    www = new WWW(my_url);
    yield return www;
    if (!string.IsNullOrEmpty(www.error))
        reqStat(false);
    else
        reqStat(true);
}

IEnumerator SecondRequest(Action<bool> reqStat)
{
    www = new WWW(my_url);
    yield return www;
    if (!string.IsNullOrEmpty(www.error))
        reqStat(false);
    else
        reqStat(true);
}

IEnumerator ThirdRequest(Action<bool> reqStat)
{
    www = new WWW(my_url);
    yield return www;
    if (!string.IsNullOrEmpty(www.error))
        reqStat(false);
    else
        reqStat(true);
}

IEnumerator FourthRequest(Action<bool> reqStat)
{
    www = new WWW(my_url);
    yield return www;
    if (!string.IsNullOrEmpty(www.error))
        reqStat(false);
    else
        reqStat(true);
}

用法:

void Init()
{
    StartCoroutine(doSequentialStuff());
}

IEnumerator doSequentialStuff()
{
    bool reqStat = false;

    //Do first request then wait for it to return
    yield return FirstRequest((status) => { reqStat = status; });

    //Do second request then wait for it to return
    if (reqStat)
        yield return SecondRequest((status) => { reqStat = status; });

    //Do third request then wait for it to return
    if (reqStat)
        yield return ThirdRequest((status) => { reqStat = status; });

    //Do fourth request then wait for it to return
    if (reqStat)
        yield return FourthRequest((status) => { reqStat = status; });
}

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