Awaiting simple callback function about asyncawait HOT 5 CLOSED

Hi @lucaswxp,

Is the getResults() function in your own API? or are you consuming it from some other API? Depending on which case, you can use it with asyncawait as follows:

Creating getResults() to work like a node-style asynchronous function:

// Define the function
var getResults = async.cps (function (param) {
    // use throw and return stmts in here to pass err/result back to the caller's callback
    if (param !== 'foo') throw new Error('param must equal "foo"');
    var result = await (someAsyncComputation(param));
    return result;
});

// Use the function - its just a normal node-style call
getResults('foo', function (err, result) {
    if (err) /* handle error */
    doSomethingWith(result);
});

Consuming a node-style getResults() asynchronous function:

var Promise = require('bluebird');
var getResultsAsync = Promise.promisify(require('the api containing getResults').getResults);

// Use the function
var myFunction = async (function () {
    var result = await (getResultsAsync());
    ...
});

Note that the next release of asyncawait will be able to await node-style functions directly without the need to promisify them first. But for now, that's how to do it. Has this answered your question?

from asyncawait.

Thanks @yortus! But would it also work if my callback only takes one parameter? Like function(result) instead of function(err, result)?

Good to know that feature will be coming in next release!

Btw, getResults() is from my own API.

from asyncawait.

@lucaswxp async.cps(...) always creates node-style callbacks, so the callback will always be called with the (err, result) convention, even if an error never occurs. If you want your code to be interoperable in node-land, I think it's best to stick to this convention, as almost everything expects this.

from asyncawait.

Yes, of course! I was new to node when designed the API, so didn't know the convention at the time. Thanks for the feedback @yortus.

from asyncawait.

What if callback expects (err, arg1, arg2, ...)? Returing [result1, result2, ...] from async.cps won't do the trick, obviously. There may be some async.cps variant, e.g. async.starCps.

from asyncawait.