如果我多次拒绝/解决Kriskowal q中的问题，会发生什么? [英] What happens if i reject / resolve multiple times in Kriskowal's q?

问题描述

我正在研究Promise模式，并将kriskowal的q用于node.js，

I'm studying the promises pattern and using kriskowal's q for node.js,

具有以下代码段:

var deferred = Q.defer();
try {
    messageData = JSON.parse(message);
} catch (e) {
    global.logger.warn('Error parsing JSON message.');
    deferred.reject(e);
}
...
if (some_reason)
    deferred.resolve(something);
...
return deferred.promise;

如果解析器都失败并且 some_reason 为真该怎么办?

What if both the parser fails and some_reason is true?

执行是否会从拒绝通过解析开始，并且两个promise的方法在不同的时间被调用，从而产生错误?

Will the execution procede from rejecting through resolving and both promise's method be called at different times, thus generating a bug?

我应该避免多次调用拒绝/解决吗?

Should i avoid to call reject/resolve multiple times?

推荐答案

由于承诺只能解决一次(对于任一实现或被拒绝)，则第一个解决方案将获胜，任何其他调用均将被忽略.来自文档:

Since promises can only resolve once (to either fulfilled or rejected), the first resolution wins and any further calls will be ignored. From the docs:

在所有已兑现承诺(即履行或拒绝)的情况下，解决方案都是永久性的，无法重置.尝试呼叫解决，拒绝或通知诺言已经解决的操作将是无操作的.

In all cases where a promise is resolved (i.e. either fulfilled or rejected), the resolution is permanent and cannot be reset. Attempting to call resolve, reject, or notify if promise is already resolved will be a no-op.

我应该避免多次调用拒绝/解决吗?

Should i avoid to call reject/resolve multiple times?

您甚至可以设计应用程序，让两个方法相互竞争"以解决延迟问题，但通常应避免这样做，以减少读者的困惑.

You can even design your application letting two methods "race" against each other to resolve a deferred, but in general it should be avoided to reduce confusion of a reader.

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