承诺RxJS5中的可观察对象

Question

Is it possible to create observables similar to how Bluebird's promisify works?

Reference: http://bluebirdjs.com/docs/api/promise.promisify.html

Regular way to handle callbacks

someFunc = callback => handleCallback(callback)

Handling callbacks with a Promise

someFunc = callback => (
    new Promise(resolve => handleCallback(resolve))
    .then(callback)
)

Fancy Bluebird wrapper around manually handling callbacks with a Promise

someFunc = callback => (
    Promise.promisify(handleCallback)()
    .then(callback)
)

In the same vein, a similar requirement is required for observables:

Observable Creation

someFunc = callback => (
    Rx.Observable
    .create(observer => (
        handleCallback(() => observer.next())
    ))
    .subscribe(callback)
)

Callback Observable Wrapper

someFunc = callback => (
    Rx.Observable
    .fromCallback(handleCallback)
    .subscribe(callback)
)

Answer 1

The proper way to handle this is with the bindCallback method.

The solution to this problem would be:

someFunc = callback => (
    Rx.Observable
    .bindCallback(handleCallback)()
    .subscribe(callback)
)

Since bindCallback returns a function, the arguments you'd pass in before the final callback arg are passed into the returned function.

There's also bindNodeCallback which is exactly the same except the first arg returned is a possible error message as you'd normally see in Node.js callbacks.

Since both of these methods only fire once and then automatically get unsubscribed, you may want to use fromEventPattern instead depending on your needs. It will keep firing observer.next() anytime the callback is called.