Remove ClassCallCheck, possibleConstructorReturn in loose mode #4850

hzoo · 2016-11-16T19:55:06Z

Q	A
Bug fix?
Breaking change?
New feature?	yes
Deprecations?
Spec compliancy?
Tests added + pass?	yes
Fixed tickets
License	MIT
Doc PR
Dependency Changes

cc @developit

codecov-io · 2016-11-16T21:06:34Z

Codecov Report

Merging #4850 into 7.0 will increase coverage by <.01%.
The diff coverage is 91.66%.

@@            Coverage Diff             @@
##              7.0    #4850      +/-   ##
==========================================
+ Coverage   85.21%   85.21%   +<.01%     
==========================================
  Files         284      284              
  Lines        9958     9966       +8     
  Branches     2780     2785       +5     
==========================================
+ Hits         8486     8493       +7     
  Misses        971      971              
- Partials      501      502       +1

Impacted Files	Coverage Δ
packages/babel-helpers/src/helpers.js	`100% <100%> (ø)`	⬆️
...bel-plugin-transform-es2015-classes/src/vanilla.js	`90.9% <90.9%> (+0.27%)`	⬆️
packages/babel-traverse/src/visitors.js	`85.71% <0%> (-0.96%)`	⬇️

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loganfsmyth · 2016-11-16T22:20:33Z

Wasn't it possibleConstructorReturn that @developit was asking about?

developit · 2016-11-16T22:29:58Z

Both actually. I'm looking for a way to say "hey, don't worry about protecting classes, they are internal to my module anyway".

DrewML · 2016-11-17T00:16:45Z

Not that I have anything against this change, but I'm just curious to know what the use-case is @developit. Performance?

developit · 2016-11-17T00:25:29Z

Performance and file size. I use codemods or avoid classes entirely, with this in place it would be more viable.

hzoo · 2016-11-17T00:30:22Z

@developit oh and you can also check out babili's plugins + babel codemods

DrewML · 2016-11-17T00:30:44Z

Part of me wonders if these things should just be part of loose mode for es2015-classes, rather than separate options. Thoughts @hzoo?

developit · 2016-11-17T00:32:51Z

@hzoo think babili would cover stripping these? That would get me to upgrade to 6 for sure! 😂

developit · 2016-11-17T00:34:45Z

@DrewML huge fringe benefit of doing that would be that the es2015 preset would be able to enable these mods with a single option. Currently disassembling that preset is a bit of a hard battle see modify-babel-preset haha).

Perhaps another option is a "minimal" mode? Or maybe that's encroaching on Babili territory.

DrewML · 2016-11-17T00:40:16Z

I think minimal mode was the initial intent of loose (but who knows at this point).

Babel 5 docs on loose mode were:

Loose mode enables certain transformers to generate cleaner output that lacks specific ES6 edgecases. These edgecases are either unlikely to appear in your code or the inclusion of them introduces significant overhead.

As a result of loose mode code will execute faster and be much more readable and comparable to the original but will deviate from the spec in slight ways.

I kind of interpret that as "generate the minimal amount of changes to make the code work, and ignore edge-cases where someone could do something bad"

developit · 2016-11-17T00:46:03Z

That is certainly how I think of it. It would be a very compelling option to have handy, at least for me. Tends to be like 300-500 bytes, which for small libs like preact is a heck of a lot (10%!).

DrewML · 2016-11-17T04:24:37Z

@hzoo Thoughts/Opinions on combining this into loose mode?

hzoo · 2016-11-17T04:34:07Z

We could? I guess it would be a "breaking change" still? although most that use loose mode wouldn't care about it anyway

developit · 2016-11-17T04:38:14Z

It be breaking for anything that is relying on calling constructors to throw (for whatever reason, I can't think of a good one, maybe some over-testing?). It's just the preset though and I would guess as you said, those are not the people running in loose mode. Also since loose was only added in 6.13 (?) it seems like it'd be not quite as widely used yet.

hzoo · 2016-11-17T05:21:08Z

This changes the plugin not the preset so it would affect everyone using the option which should of been there since the beginning? Yeah it's removing a throw check so it wouldn't break anything in the opposite way

DrewML · 2016-11-17T17:11:58Z

I guess this kind of leads to the bigger question of "what is a breaking change" in these options. In theory, we could never add any features to loose mode, because any additional optimization could always be a breaking change.

Semver is hard :(

Download · 2017-04-07T14:43:04Z

Using loose mode is the way to go for both classCallCheck and possibleConstructorReturn if you ask me.

I would like for Babel to generate code that is as close to ES6 compliant as possible under normal circumstances, then use loose mode to drop every line of code that is not strictly necessary to make stuff just work. It means in loose mode you can do stuff that is against spec... But probably you will dev in strict mode and catch such uses there. Once it's in production, use loose mode for max. performance.

Having a single toggle on the preset would be infinitely more valuable than having to control each plugin separately.

developit · 2017-04-07T14:55:35Z

Also makes fall-through from presets like latest easier since it's just the existing loose option, right?

hzoo · 2017-04-07T14:56:48Z

Yes it should although fyi latest is deprecated since env covers all it's functionality

developit · 2017-04-07T14:57:41Z

You know I'm behind on all that stuff (still using 5 in places haha)

hzoo · 2017-04-07T14:58:37Z

😅 can someone just make the auto upgrade from 5 to 6 bot

developit · 2017-04-07T15:01:44Z

@hzoo still produces larger output for some reason, need to look into why. I'm basically only using babel to convert let and const to var without caring about TDZ or block scoping.

hzoo · 2017-06-09T22:13:24Z

...ugin-transform-es2015-classes/test/fixtures/loose-classCallCheck/with-superClass/expected.js

@@ -0,0 +1,40 @@
+function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }


Do we want to remove the checks here too?

function _inheritsLoose(subclass, superClass) { subClass.prototype = Object.create(superClass && superClass.prototype); subClass.prototype.constructor = subClass; if (superClass) { subClass.__proto__ = superClass; } }

Definitely. My view here is that people using loose mode classes are just asking for a direct replacement for the ES5 equivalent.

hzoo · 2017-06-09T22:18:41Z

...ugin-transform-es2015-classes/test/fixtures/loose-classCallCheck/with-superClass/expected.js

+  function C() {
+    woops.super.test();
+
+    var _this = _B.call(this) || this;


can drop || this as well

Download · 2017-06-15T23:04:03Z

@hzoo Loving what you are doing here! Can't wait for it to be merged and released!

hzoo · 2017-06-19T15:49:20Z

...ugin-transform-es2015-classes/test/fixtures/loose-classCallCheck/with-superClass/expected.js

+
+  function A(track) {
+    if (track !== undefined) {
+      var _this = _B.call(this, track) || this;


and remove || this I guess?

developit · 2017-06-19T17:50:16Z

packages/babel-helpers/src/helpers.js

+  (function (subClass, superClass) {
+    subClass.prototype = Object.create(superClass && superClass.prototype);
+    subClass.prototype.constructor = subClass;
+    if (superClass) {


Thoughts on also removing this check?

because we would assume superClass is not null? like class extends null or class extends expression

good call, I was thinking it would always be appropriate to throw an exception but I stand corrected! :)

Ok we can just assume in loose mode that the superClass is non-null and has a prototype to get

(function (subClass, superClass) { subClass.prototype = Object.create(superClass.prototype); subClass.prototype.constructor = subClass; subClass.__proto__ = superClass; })

hzoo · 2017-06-23T15:05:46Z

packages/babel-helpers/src/helpers.js

@@ -377,6 +377,16 @@ helpers.inherits = template(`
  })
 `);

+helpers.inheritsLoose = template(`
+  (function (subClass, superClass) {
+    subClass.prototype = Object.create(superClass && superClass.prototype);


I guess we would be able to remove the check here too then @developit? superClass &&

hzoo · 2017-06-23T15:06:29Z

.../babel-plugin-transform-es2015-classes/test/fixtures/loose/accessing-super-class/expected.js

    woops.super.test();

-    var _this = babelHelpers.possibleConstructorReturn(this, _Foo.call(this));
+    var _this = _Foo.call(this) || this;


should we remove || this?

If we do, we'd have to remove the whole var _this = (and all the _thiss) too. I think this is fine for now.

hmm. this seems important.

jridgewell · 2017-06-23T18:00:39Z

.../babel-plugin-transform-es2015-classes/test/fixtures/loose/accessing-super-class/expected.js

    woops.super.test();

-    var _this = babelHelpers.possibleConstructorReturn(this, _Foo.call(this));
+    var _this = _Foo.call(this) || this;


If we do, we'd have to remove the whole var _this = (and all the _thiss) too. I think this is fine for now.

hzoo · 2017-06-26T19:23:37Z

Ok will merge and someone can do #4850 (comment) as a followup issue/PR

hzoo · 2017-06-26T19:23:55Z

Also something about travis is messed up (circle ci passes + local)

Download · 2017-07-01T14:06:43Z

@hzoo Is there a way to test this in my project before it is released to NPM?

hzoo · 2017-07-01T14:28:42Z

I could some better docs for this (or a utility to make it easy) but yeah you can just overwrite your node_modules? Like literally replace the 2 files that we changed. You can probably just run the src/index.js through babeljs.io/repl and then replace the lib/index.js in node_modules and add that helper to test it

Download · 2017-07-03T10:57:54Z

@hzoo Ok. I guess that's a bit too far outside of my comfort zone :) I guess I'll wait until the next alpha makes it to NPM. :)

hzoo · 2017-07-12T23:14:33Z

https://github.com/babel/babel/releases/tag/v7.0.0-alpha.15

babel/babel#4850

hzoo added the PR: New Feature 🚀 A type of pull request used for our changelog categories label Nov 17, 2016

hzoo mentioned this pull request Apr 6, 2017

optional _classCallCheck? #798

Closed

removeClassCallCheck option

4081f3e

hzoo changed the title ~~removeClassCallCheck option~~ Remove ClassCallCheck in loose mode Jun 9, 2017

hzoo force-pushed the removeClassCallCheck-option branch from 7677c86 to 6b31d13 Compare June 9, 2017 22:12

hzoo changed the base branch from master to 7.0 June 9, 2017 22:12

hzoo changed the title ~~Remove ClassCallCheck in loose mode~~ Remove ClassCallCheck, possibleConstructorReturn in loose mode Jun 9, 2017

hzoo commented Jun 9, 2017

View reviewed changes

remove possibleConstructorReturn in loose mode as well

cdca54a

hzoo force-pushed the removeClassCallCheck-option branch from 6b31d13 to cdca54a Compare June 9, 2017 22:42

hzoo commented Jun 19, 2017

View reviewed changes

create and use a inheritsLoose helper

8a4ab08

developit reviewed Jun 19, 2017

View reviewed changes

hzoo requested review from loganfsmyth and jridgewell June 19, 2017 19:32

hzoo commented Jun 23, 2017

View reviewed changes

jridgewell approved these changes Jun 23, 2017

View reviewed changes

remove superClass truthy check

4fdff56

xtuc approved these changes Jun 26, 2017

View reviewed changes

hzoo merged commit bb5528b into 7.0 Jun 26, 2017

xtuc deleted the removeClassCallCheck-option branch June 27, 2017 14:04

This was referenced Jun 29, 2017

Active development? What is missing for 1.0? Download/mics#1

Closed

Make compatible with Babel loose mode optimizations Download/mics#6

Open

hzoo mentioned this pull request Sep 16, 2017

Babel 7 twbs/bootstrap#23966

Merged

2 tasks

hzoo mentioned this pull request Oct 18, 2017

Some of these can be incorporated in Babel yiminghe/babel-runtime-loose#2

Closed

yiminghe added a commit to yiminghe/babel-runtime-loose that referenced this pull request Oct 30, 2017

optimize loose.

68930db

babel/babel#4850

hzoo mentioned this pull request Dec 12, 2017

Add support for extending builtins #7020

Merged

lock bot added the outdated A closed issue/PR that is archived due to age. Recommended to make a new issue label Oct 6, 2019

lock bot locked as resolved and limited conversation to collaborators Oct 6, 2019

		@@ -0,0 +1,40 @@
		function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }

Remove ClassCallCheck, possibleConstructorReturn in loose mode #4850

Remove ClassCallCheck, possibleConstructorReturn in loose mode #4850

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