or ... you could bypass these low-level promise-abstractions altogether, and elegantly solve the actual integration-level task asked by your pm - with a single, easy-to-debug, throwaway recursive-callback (which will likely work exactly the same 10 years from now, while god-knows how the magic will evolve with promises in that time).
```javascript /* * example.js * * example usage: * $ FOR_HOW_LONG=1000 node example.js * * example output: * 0 ms - start recusive-callback * 1005 ms - waited for server and db to initialize * 1007 ms - read file example.js which had 2519 characters * 1844 ms - fetched 1270 bytes of data from https://www.example.com * 1844 ms - finished recursive-callback */ /*jslint bitwise: true, browser: true, maxerr: 4, maxlen: 100, node: true, nomen: true, regexp: true, stupid: true */ 'use strict'; var modeNext, onNext, timeStart, tmp; onNext = function (error, data) { // For reject: if (error) { console.error(error); return; } modeNext += 1; switch (modeNext) { case 1: timeStart = Date.now(); console.log((Date.now() - timeStart) + ' ms - ' + 'start recusive-callback'); // sleep setTimeout(onNext, process.env.FOR_HOW_LONG); break; case 2: console.log((Date.now() - timeStart) + ' ms - ' + 'waited for server and db to initialize'); onNext(); break; case 3: // read this file require('fs').readFile(__filename, 'utf8', onNext); break; case 4: console.log((Date.now() - timeStart) + ' ms - ' + 'read file ' + __filename + ' which had ' + data.length + ' characters'); onNext(); break; case 5: // fetch data from https://www.example.js require('https').request( require('url').parse('https://www.example.com'), function (response) { onNext(null, response); } ) // handle http-request error .on('error', onNext) .end(); break; case 6: // handle http-response error data.on('error', onNext); // collect http-response chunks tmp = []; data.on('data', function (chunk) { tmp.push(chunk); }); // concatenate http-response chunks data.on('end', function () { onNext(null, Buffer.concat(tmp)); }); break; case 7: console.log((Date.now() - timeStart) + ' ms - ' + 'fetched ' + data.length + ' bytes of data from https://www.example.com'); onNext(); break; case 8: console.log((Date.now() - timeStart) + ' ms - ' + 'finished recursive-callback'); break; } }; modeNext = 0; onNext(); ``` > On 13 Apr 2018, at 12:07 AM, Luiz Felipe Frazão Gonçalves > <luizfelipefrazaogoncal...@gmail.com> wrote: > > One new proposal for EcmaScript. > > Promised Functions > > Like async/await, the promised functions would be preceded by a keyword. In > the case, promised, it would change the default behavior of the function, > making it behave as a promise. > > I will use as an example a classic sleep function: > > function sleep(forHowLong) { > return new Promise((resolve, reject) => { > setTimeout(function() { > resolve(); > > /** > * For reject: > * > * reject(Error('Some error')); > */ > }, forHowLong); > }); > } > I think to avoid the huge amount of callbacks, there should be a syntax > similar to this: > > promised function sleep(forHowLong) { > setTimeout(function() { > this.resolve(); // could even create a keyword like "resolve" > > /** > * For reject: > * > * this.reject(Error('Some error')); > */ > }, forHowLong); > } > Note that the hypothetical keyword "promised" before the function statement > makes it act as a promise. > > Just a crazy idea I had. :) > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss > On 13 Apr 2018, at 12:19 AM, Tab Atkins Jr. <jackalm...@gmail.com> wrote: > > On Thu, Apr 12, 2018 at 9:07 AM, Luiz Felipe Frazão Gonçalves > <luizfelipefrazaogoncal...@gmail.com > <mailto:luizfelipefrazaogoncal...@gmail.com>> wrote: >> One new proposal for EcmaScript. >> >> Promised Functions >> >> Like async/await, the promised functions would be preceded by a keyword. In >> the case, promised, it would change the default behavior of the function, >> making it behave as a promise. >> >> I will use as an example a classic sleep function: >> >> function sleep(forHowLong) { >> return new Promise((resolve, reject) => { >> setTimeout(function() { >> resolve(); >> >> /** >> * For reject: >> * >> * reject(Error('Some error')); >> */ >> }, forHowLong); >> }); >> } >> >> I think to avoid the huge amount of callbacks, there should be a syntax >> similar to this: > > Some of these callbacks aren't necessary: > > function sleep(forHowLong) { > return new Promise(resolve=>setTimeout(resolve, forHowLong)); > } > > Tho even if you do use all the same callbacks, just formatting it > properly helps: > > function sleep(forHowLong) { > return new Promise(resolve=>setTimeout(_=>resolve(), forHowLong)); > } > > ~TJ > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org <mailto:es-discuss@mozilla.org> > https://mail.mozilla.org/listinfo/es-discuss > <https://mail.mozilla.org/listinfo/es-discuss> > On 13 Apr 2018, at 1:55 AM, Michał Wadas <michalwa...@gmail.com> wrote: > > Is it codyfing of glorious The Deferred anti-pattern? > https://github.com/petkaantonov/bluebird/wiki/Promise-Anti-patterns#the-deferred-anti-pattern > > <https://github.com/petkaantonov/bluebird/wiki/Promise-Anti-patterns#the-deferred-anti-pattern> > > On Thu, Apr 12, 2018 at 6:07 PM, Luiz Felipe Frazão Gonçalves > <luizfelipefrazaogoncal...@gmail.com > <mailto:luizfelipefrazaogoncal...@gmail.com>> wrote: > One new proposal for EcmaScript. > > Promised Functions > > Like async/await, the promised functions would be preceded by a keyword. In > the case, promised, it would change the default behavior of the function, > making it behave as a promise. > > I will use as an example a classic sleep function: > > function sleep(forHowLong) { > return new Promise((resolve, reject) => { > setTimeout(function() { > resolve(); > > /** > * For reject: > * > * reject(Error('Some error')); > */ > }, forHowLong); > }); > } > I think to avoid the huge amount of callbacks, there should be a syntax > similar to this: > > promised function sleep(forHowLong) { > setTimeout(function() { > this.resolve(); // could even create a keyword like "resolve" > > /** > * For reject: > * > * this.reject(Error('Some error')); > */ > }, forHowLong); > } > Note that the hypothetical keyword "promised" before the function statement > makes it act as a promise. > > Just a crazy idea I had. :) > > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org <mailto:es-discuss@mozilla.org> > https://mail.mozilla.org/listinfo/es-discuss > <https://mail.mozilla.org/listinfo/es-discuss> > > > _______________________________________________ > es-discuss mailing list > es-discuss@mozilla.org > https://mail.mozilla.org/listinfo/es-discuss
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