如果我在Kriskowal的q中多次拒绝/解决会怎么样？

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

我正在研究promises模式并使用kriskowal的q作为node.js，

having this snippet:

有这个片段：

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;

What if both the parser fails and some_reason is true?

如果解析器失败且some_reason为真，该怎么办？

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

执行会从拒绝通过解析进行，并且会在不同的时间调用promise的方法，从而产生错误吗？

Should i avoid to call reject/resolve multiple times?

我应该避免多次致电拒绝/解决？

1 个解决方案

#1

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:

由于promises只能解析一次（要么已完成或被拒绝），第一个分辨率将获胜，任何进一步的调用都将被忽略。来自文档：

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.

在承诺得到解决（即满足或拒绝）的所有情况下，解决方案都是永久性的，无法重置。如果承诺已经解决，尝试呼叫解决，拒绝或通知将是无操作。

Should i avoid to call reject/resolve multiple times?

我应该避免多次致电拒绝/解决？

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.

您甚至可以设计您的应用程序，让两种方法相互“竞争”以解决延迟，但一般来说应该避免减少读者的混淆。

#1