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child_process: name anonymous functions #9880

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brad-decker
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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.

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

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

child.stdout.addListener('data', function(chunk) {
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@mscdex mscdex Dec 1, 2016

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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) {

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

if (options.timeout > 0) {
timeoutId = setTimeout(function() {
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Same here, this could be:

timeoutId = setTimeout(function delayedKill() {

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👍

}

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

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

@mscdex
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mscdex commented Dec 1, 2016

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.

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@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?

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mscdex commented Dec 1, 2016

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) {

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@mscdex suggested changes implemented. Thanks for your feedback.

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mscdex commented Dec 1, 2016

LGTM

@Trott
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Trott commented Dec 1, 2016

@brad-decker
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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

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Trott commented Dec 2, 2016

@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/

'Use options.stdio instead.');
const _deprecatedCustomFds = internalUtil.deprecate(
function deprecateCustomFds(options) {
options.stdio = options.customFds.map(function(fd) {
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Nit: maybe use an arrow function for this? It should fit in a single line.

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@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.

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@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?

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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?

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Yeah, I would only remove the return statement.

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

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

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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.

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No problem! Thanks for the feedback. 👍

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Addressed in new commit and rebased/squashed

@@ -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) {
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Feel free to ignore, but perhaps name this onNewListener. Same with onRemoveListener.

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yeah i think onNewListener is better naming convention. 👍

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

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

@brad-decker
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Thanks @jasnell

jasnell pushed a commit that referenced this pull request Dec 5, 2016
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>
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jasnell commented Dec 5, 2016

Landed in bbed075. Thank you!

@jasnell jasnell closed this Dec 5, 2016
Fishrock123 pushed a commit that referenced this pull request Dec 6, 2016
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>
jmdarling pushed a commit to jmdarling/node that referenced this pull request Dec 8, 2016
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>
@MylesBorins MylesBorins added the baking-for-lts PRs that need to wait before landing in a LTS release. label May 8, 2017
@MylesBorins 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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8 participants