child_process: name anonymous functions #9880

brad-decker · 2016-12-01T16:00:48Z

Checklist

make -j8 test (UNIX), or vcbuild test nosign (Windows) passes
commit message follows commit guidelines

Affected core subsystem(s)

child_process

Description of change

Per #8913 i've named anonymous callback handlers.

I have some mixed styling in here because i'm still going over the message log from #8913 and trying to determine best practices. Is the correct implementation of current anonymous functions just to apply a name to those functions without lifting them out of the function call and using arrow functions?

In particular this file has no arrow functions in it yet, so i would assume we'd want to stick to using:

setTimeout(function name() {}, options.timeout);

over

const name = () => {};
setTimeout(name, options.timeout);

if that's the case is there a preferred naming schema for things like setTimeout? The names on some of these seem to be moving towards the verbose, ex:

child.stderr.addListener('data', function stderrAddListenerCallback(){});

Definitely ready to make changes to this to make it compliant.

mscdex · 2016-12-01T16:04:16Z

lib/child_process.js

  }

  if (child.stdout) {
    if (encoding)
      child.stdout.setEncoding(encoding);

-    child.stdout.addListener('data', function(chunk) {


Why not name the function inline here instead?:

child.stdout.addListener('data', function onChildStdout(chunk) {

or even shorter:

child.stdout.on('data', function onChildStdout(chunk) {

mscdex · 2016-12-01T16:05:45Z

lib/child_process.js

@@ -247,17 +247,18 @@ exports.execFile = function(file /*, args, options, callback*/) {
  }

  if (options.timeout > 0) {
-    timeoutId = setTimeout(function() {


Same here, this could be:

timeoutId = setTimeout(function delayedKill() {

mscdex · 2016-12-01T16:06:31Z

lib/child_process.js

  }

  if (child.stderr) {
    if (encoding)
      child.stderr.setEncoding(encoding);

-    child.stderr.addListener('data', function(chunk) {


mscdex · 2016-12-01T16:10:25Z

I think arrow functions are fine for the most part, but if they result in the addition of new lines of code, I don't think it's really worth it at that point. Since the purpose is to give better stack traces, just adding a name to the anonymous functions is easiest and requires less change.

brad-decker · 2016-12-01T16:12:49Z

@mscdex Thanks for the feedback, working on making those changes now. One question,

var _deprecatedCustomFds = internalUtil.deprecate(function deprecateCustomFds(options) {
  options.stdio = options.customFds.map(function(fd) {
    return fd === -1 ? 'pipe' : fd;
  });
}, 'child_process: options.customFds option is deprecated. ' +
   'Use options.stdio instead.');

this first line is way too long. Do you happen to have a recommendation on function name for this particular callback? Or should I just break to a new line to follow linting and leave a verbose function name?

mscdex · 2016-12-01T16:16:14Z

Without checking with the linter, I'd be fine with something like:

const _deprecatedCustomFds =
  internalUtil.deprecate(function deprecateCustomFds(options) {

or

const _deprecatedCustomFds = internalUtil.deprecate(
  function deprecateCustomFds(options) {

brad-decker · 2016-12-01T16:31:08Z

@mscdex suggested changes implemented. Thanks for your feedback.

mscdex · 2016-12-01T16:34:05Z

LGTM

Trott · 2016-12-01T23:44:39Z

CI: https://ci.nodejs.org/job/node-test-pull-request/5093/

brad-decker · 2016-12-02T03:30:37Z

Looks like 3 checks failed. Having a little confusion with navigating the CI results to find the issues/logs to aid in correcting these failures. @mscdex @Trott

Trott · 2016-12-02T04:05:38Z

@brad-decker Looks like somebody thought there was something wrong with CI and terminated a whole bunch of jobs, including this one. (I had started a lot of them because: Code & Learn.) Bummer. Oh well. Here's another one: https://ci.nodejs.org/job/node-test-pull-request/5096/

lpinca · 2016-12-02T10:04:53Z

lib/child_process.js

-   'Use options.stdio instead.');
+const _deprecatedCustomFds = internalUtil.deprecate(
+  function deprecateCustomFds(options) {
+    options.stdio = options.customFds.map(function(fd) {


Nit: maybe use an arrow function for this? It should fit in a single line.

@lpinca The goal would be getting rid of the anonymous callback functions, so if we were to go the route of an arrow function it'd be declaring a new const above this declaration that defines the callback function, then passing that const to internalUtil.deprecate. I'm 👍 on doing that, but I want to make sure that that would fit the overall code style/design patterns we're wanting to achieve.

@brad-decker yup, the reason for my comment was that the function was still anonymous.
Maybe it's better to just give it a name?

I was actually thinking you were talking about changing

function deprecateCustomFds(options) {

To a const, so i misunderstood you. totally missed the call to map.

const mapCustomFds = (fd) => { return fd === -1 ? 'pipe' : fd; }; const _deprecatedCustomFds = internalUtil.deprecate( function deprecateCustomFds(options) { options.stdio = options.customFds.map(mapCustomFds); }, 'child_process: options.customFds option is deprecated. ' + 'Use options.stdio instead.' );

I wrapped the block for the arrow function in curlys to avoid lint error for no-confusing-arrow. Does this solution look okay to you?

Yeah, I would only remove the return statement.

const mapCustomFds = (fd) => fd === -1 ? 'pipe' : fd;

when removing the return statement i get the no-confusing-arrow lint rule being thrown complaining about using arrow functions ambigiously with conditional expressions.

Oh ops, sorry so maybe just give the original function the mapCustomFds name without using the arrow function.

I think it's the cleanest thing to do.

Sorry again for the confusion.

No problem! Thanks for the feedback. 👍

Addressed in new commit and rebased/squashed

cjihrig · 2016-12-02T17:26:20Z

lib/child_process.js

@@ -70,10 +70,10 @@ exports._forkChild = function(fd) {
  p.open(fd);
  p.unref();
  const control = setupChannel(process, p);
-  process.on('newListener', function(name) {
+  process.on('newListener', function newListenerCallback(name) {


Feel free to ignore, but perhaps name this onNewListener. Same with onRemoveListener.

yeah i think onNewListener is better naming convention. 👍

resolved in new commit and rebased.

Per nodejs#8913 i've named anonymous callback handlers, This commit is just a first stab at this looking for community feedback on style/naming conventions

Trott · 2016-12-05T06:14:07Z

CI: https://ci.nodejs.org/job/node-test-pull-request/5196/

jasnell

LGTM! Thank you for the PR and for participating in the code-and-learn!

brad-decker · 2016-12-05T15:19:56Z

Thanks @jasnell

Refs: #8913 PR-URL: #9880 Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Brian White <mscdex@mscdex.net>

jasnell · 2016-12-05T15:38:39Z

Landed in bbed075. Thank you!

Refs: #8913 PR-URL: #9880 Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Brian White <mscdex@mscdex.net>

Refs: nodejs#8913 PR-URL: nodejs#9880 Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Brian White <mscdex@mscdex.net>

nodejs-github-bot added the child_process Issues and PRs related to the child_process subsystem. label Dec 1, 2016

mscdex reviewed Dec 1, 2016

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brad-decker force-pushed the name-annoynmous-child-process branch from 2f38dd5 to f689725 Compare December 1, 2016 16:30

lpinca reviewed Dec 2, 2016

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lpinca approved these changes Dec 2, 2016

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cjihrig reviewed Dec 2, 2016

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child_process: name anonymous functions

0474df9

Per nodejs#8913 i've named anonymous callback handlers, This commit is just a first stab at this looking for community feedback on style/naming conventions

brad-decker force-pushed the name-annoynmous-child-process branch from f689725 to 0474df9 Compare December 2, 2016 18:41

cjihrig approved these changes Dec 3, 2016

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Trott added the code-and-learn Issues related to the Code-and-Learn events and PRs submitted during the events. label Dec 5, 2016

jasnell approved these changes Dec 5, 2016

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jasnell closed this Dec 5, 2016

MylesBorins added dont-land-on-v4.x labels Dec 20, 2016

MylesBorins added the baking-for-lts PRs that need to wait before landing in a LTS release. label May 8, 2017

MylesBorins removed the baking-for-lts PRs that need to wait before landing in a LTS release. label Aug 17, 2018

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child_process: name anonymous functions #9880

child_process: name anonymous functions #9880

brad-decker commented Dec 1, 2016

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child_process: name anonymous functions #9880

child_process: name anonymous functions #9880

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brad-decker commented Dec 1, 2016

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Affected core subsystem(s)

Description of change

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