解决承诺而不叫'then' [英] Resolving a Promise without calling the 'then'
问题描述
我有这段代码,这是我为名为Poolio的NPM模块编写的小型API的一部分。对于那些支持错误优先回调和Promise的人来说,我似乎是一个常见问题。在维护一致的API和API一致的返回值的同时,我们如何支持两者?例如,如果我有条件地从我的API中返回一个promise,这取决于我的lib的使用者是否提供了回调,那么我认为这有点尴尬。
I have this code that is part of a small API that I am writing for an NPM module called Poolio. The question I have seems to be a common question for those supporting error-first callbacks as well as promises- how do we support both while maintaining consisent APIs and consistent return values from the API? For example, if I conditionally return a promise from my API, depending on whether the consumer of my lib provides a callback, that is a little awkward in my opinion.
lib的使用者可以提供回调或使用Promise then函数,但不能同时使用两者。
The consumer of the lib can provide a callback or use the Promise then function, but not both.
这里是我的lib导出的一个函数,谨在此声明:
Here is a function exported by my lib, that I would like to promisify:
Pool.prototype.any = function (msg, cb) {
var workId = this.counter++;
var self = this;
return new Promise(function (resolve, reject) {
if (typeof cb === 'function') {
self.resolutions.push({
workId: workId,
cb: cb
});
}
else {
self.resolutions.push({
workId: workId,
resolve: resolve,
reject: reject
});
}
if (this.available.length > 0) {
var cp = this.available.shift();
cp.workId = workId;
cp.send(msg);
}
else {
self.msgQueue.push({
workId: workId,
msg: msg
});
}
});
};
我的问题是-如果用户在原始函数参数中提供了回调函数,我该如何解决诺言而不叫那么?
对不起,很难解释,但希望您能理解。
my question is - if the user provides a callback function in the original function arguments, how can I resolve the promise without calling 'then'? Sorry it's hard to explain but hopefully you can understand.
还有一个有趣的问题:
从不解决的诺言会导致内存泄漏吗?
also there is this interesting question: Do never resolved promises cause memory leak?
推荐答案
实际上非常简单。
基本上,您可以这样做:
Basically you do this:
var promise = new Promise(function (resolve, reject) { /*....*/});
if (typeof cb === 'function') {
promise.then(cb);
} else {
return promise;
}
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