util: add util.types.isBoxedPrimitive #22620

BridgeAR · 2018-08-31T13:41:34Z

Checking all boxed primitives individually requires to cross the C++
barrier multiple times besides being more complicated than just a
single check.

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
tests and/or benchmarks are included
documentation is changed or added
commit message follows commit guidelines

Checking all boxed primitives individually requires to cross the C++ barrier multiple times besides being more complicated than just a single check.

nodejs-github-bot · 2018-08-31T13:41:36Z

@BridgeAR build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/741/pipeline

BridgeAR · 2018-08-31T13:43:00Z

CI https://ci.nodejs.org/job/node-test-pull-request/16895/

benjamingr · 2018-08-31T23:48:07Z

test/parallel/test-util-types.js

@@ -68,6 +69,15 @@ for (const [ value, _method ] of [
  }
 }

+// Check boxed primitives.


Maybe add some negative results to the test?

This seems somewhat redundant to me, since this is just a helper combined out of different helpers that are already tested against all other types.
But I'll add negative results as well if you feel strongly about it!

I think it makes sense to test - but don't feel strongly about it.

targos · 2018-09-01T08:29:31Z

Maybe name it isPrimitiveObject? I don't see the term "boxed" being used in the ecmascript specification or on MDN.

Edit: It's more consistent with the names of the individual methods (there is no isBoxedBoolean)

jdalton · 2018-09-01T19:25:29Z

@targos You'll sometimes see boxed, unboxed, and auto-boxing come up in conversations. It's used to describe what happens when you access a property on a primitive value. For example:

"a".trim // auto-boxes primitive "a" to access the property "trim"
"a".a = 1 // box primitive for property assignment then unbox after
"a".a // undefined because the property was assigned to the boxed value which was discarded

MDN mentions boxing here , here, and here.

That said, isPrimitiveObject is more precise so 👍

BridgeAR · 2018-09-03T18:26:24Z

isPrimitiveObject sounds somewhat wrong to me. Turning it around to isObjectPrimitive seems somewhat better but still not awesome (isPrimitiveObject reminds me of an object that is primitive and I would not know what that should be. It somewhat reminds me of an plain object). However, I can not think of anything else as alternative and it does align with the other is...Object functions. Anyone else with more suggestions / reasons for either name?

addaleax · 2018-09-03T18:29:29Z

Turning it around to isObjectPrimitive seems somewhat better but still not awesome

That would imply that we’re checking for “object primitives”, i.e. primitives which have something to do with objects. The values that pass the tests are definitely not primitives, though.

BridgeAR · 2018-09-03T18:41:56Z

@addaleax

primitives which have something to do with objects

It does seems somewhat more intuitive for me (even if it's not really a primitive it is why we check for it: we want to know if it has something to do with a primitive by encapsulating one). I never heard of an "primitive object" and my head just can't get used to that name.

addaleax · 2018-09-03T18:44:57Z

I never heard of an "primitive object" and my head just can't get used to that name.

I agree that it sounds odd, but I think it’s more accurate than “object primitive”. Tbh, I think isBoxedObject or isBoxedPrimitive both are okay, even if the spec doesn’t talk about boxing with that term.

targos · 2018-09-03T18:46:54Z

(it was just a suggestion, I'm not blocking anything. Just wanted to make sure alternative names were considered)

BridgeAR · 2018-09-03T18:48:53Z

I am fine with either isBoxedPrimitive or isBoxedObject while having a preference for the former.

devsnek

isBoxedPrimitive sounds good to me.

I would also be okay with isObjectWithPrototypeThatIsOneOfThePrimitivePrototypeIntrinsics 😄

jdalton · 2018-09-03T19:24:10Z

I dig isPrimitiveObject because, as mentioned before, it fits with the existing naming convention of isXyzObject, like isBooleanObject and isNumberObject, by replacing Boolean or Number with Primitive. While more letters, Primitive for me is easier to grok at a glance than Boxed too.

Update:

I should make it clear I'm OK with the existing isBoxedPrimitive too
(isPrimitiveObject is a preference for me is all).

addaleax · 2018-09-03T19:26:43Z

Totally scientific research: https://twitter.com/addaleax/status/1036696939365052418

ljharb · 2018-09-03T20:05:23Z

It's a boxed primitive imo; a "primitive object" doesn't make sense because the two words are mutually exclusive. It's also not a boxed object, it's an object formed by boxing a primitive into an object.

(fwiw this is already polyfillable in pure JS; see https://twitter.com/ljharb/status/1036707165002559488)

jdalton · 2018-09-03T20:19:02Z

@ljharb

(fwiw this is already polyfillable in pure JS; see

Yep, and we have util.types.isNumberObject and friends too. The addition in this PR, is part of exposing helpers used to make inspect perf better (it's handy for inspect and handy for those in the ecosystem too). See #22503.

ljharb · 2018-09-03T20:25:16Z

@jdalton to clarify; that it's already polyfillable is why this is safe to expose directly as a faster and much more friendly helper :-) i'm super on board.

BridgeAR · 2018-09-03T20:33:24Z

The CI https://ci.nodejs.org/job/node-test-commit/21107/ is green by the way.

TimothyGu · 2018-09-03T20:38:46Z

Would it be worthwhile to instead implement this in JavaScript? It seems like it's possible to do so, and it's usually faster than an implementation that goes through C++.

ljharb · 2018-09-03T20:44:21Z

@TimothyGu that would require 4 try/catches around calling cached builtin methods, expecting them to throw for a true result. I would be very surprised if it was faster to do it in pure JS.

BridgeAR · 2018-09-03T21:00:01Z

I just ran a simple benchmark only for boxed numbers and it's ten times faster in C++ (this is mixed input. Using only boxed numbers as input it's two times slower):

tryNumberObject: 1255.014ms
isNumberObject: 130.553ms

Note: I optimized tryNumberObject before using it by setting the stackTraceLimit to 0. Otherwise it would be 20 times slower.

benjamingr · 2018-09-03T21:24:08Z

@TimothyGu that would require 4 try/catches around calling cached builtin methods, expecting them to throw for a true result. I would be very surprised if it was faster to do it in pure JS.

Would you mind explaining why @ljharb?

ljharb · 2018-09-03T21:34:36Z

@benjamingr because the only way to determine if something is a boxed primitive in JS, cross-realm, is to .call a brand-checking prototype method on it, and if it throws, it is one. (instanceof is never reliable) So, the algorithm would have to be basically this:

return false if it's a primitive, or a function
try/catch to see if it's got a Boolean slot, if so, return true
try/catch to see if it's got a String slot, if so, return true
try/catch to see if it's got a Symbol slot, if so, return true
try/catch to see if it's got a Number slot, if so, return true
return false

BridgeAR · 2018-09-04T19:00:49Z

If no one objects to the current name in the next 24h, I'll go ahead and land it.

The twitter poll resulted in 26% for the current name, 26% for isObjectPrimitive and 40% for isPrimitiveObject and 8% for isBoxedObject. Since the poll can not show how strongly people prefer either one, it's hopefully fine to just keep the current name.

Checking all boxed primitives individually requires to cross the C++ barrier multiple times besides being more complicated than just a single check. PR-URL: nodejs#22620 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: John-David Dalton <john.david.dalton@gmail.com> Reviewed-By: Refael Ackermann <refack@gmail.com> Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com> Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

BridgeAR · 2018-09-05T18:58:34Z

Thanks everyone.

Landed in 3209679 🎉

Checking all boxed primitives individually requires to cross the C++ barrier multiple times besides being more complicated than just a single check. PR-URL: #22620 Reviewed-By: Anna Henningsen <anna@addaleax.net> Reviewed-By: John-David Dalton <john.david.dalton@gmail.com> Reviewed-By: Refael Ackermann <refack@gmail.com> Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com> Reviewed-By: Gus Caplan <me@gus.host> Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>

Notable changes: * fs * Added a `recursive` option to `fs.mkdir` and `fs.mkdirSync`. If this option is set to `true`, non-existing parent folders will be automatically created. #21875 * Fixed fsPromises.readdir `withFileTypes`. #22832 * http2 * Added `http2stream.endAfterHeaders` property. #22843 * module * Added `module.createRequireFromPath(filename)`. This new method can be used to create a custom `require` function that will resolve modules relative to the `filename` path. #19360 * url * Added `url.fileURLToPath(url)` and `url.pathToFileURL(path)`. These methods can be used to correctly convert between `file:` URLs and absolute paths. #22506 * util * Added `util.types.isBoxedPrimitive(value)`. #22620 * Windows * The Windows msi installer now provides an option to automatically install the tools required to build native modules. #22645 * Added new collaborators: * boneskull (https://github.com/boneskull) - Christopher Hiller * The Technical Steering Committee has new members: * apapirovski (https://github.com/apapirovski) - Anatoli Papirovski * gabrielschulhof (https://github.com/gabrielschulhof) - Gabriel Schulhof PR-URL: #22932

Notable changes: * fs * Added a `recursive` option to `fs.mkdir` and `fs.mkdirSync`. If this option is set to `true`, non-existing parent folders will be automatically created. #21875 * Fixed fsPromises.readdir `withFileTypes`. #22832 * http2 * Added `http2stream.endAfterHeaders` property. #22843 * module * Added `module.createRequireFromPath(filename)`. This new method can be used to create a custom `require` function that will resolve modules relative to the `filename` path. #19360 * url * Added `url.fileURLToPath(url)` and `url.pathToFileURL(path)`. These methods can be used to correctly convert between `file:` URLs and absolute paths. #22506 * util * Added `util.types.isBoxedPrimitive(value)`. #22620 * Added new collaborators: * boneskull (https://github.com/boneskull) - Christopher Hiller * The Technical Steering Committee has new members: * apapirovski (https://github.com/apapirovski) - Anatoli Papirovski * gabrielschulhof (https://github.com/gabrielschulhof) - Gabriel Schulhof PR-URL: #22932

Notable changes: * fs * Fixed fsPromises.readdir `withFileTypes`. #22832 * http2 * Added `http2stream.endAfterHeaders` property. #22843 * util * Added `util.types.isBoxedPrimitive(value)`. #22620 * Added new collaborators: * boneskull (https://github.com/boneskull) - Christopher Hiller * The Technical Steering Committee has new members: * apapirovski (https://github.com/apapirovski) - Anatoli Papirovski * gabrielschulhof (https://github.com/gabrielschulhof) - Gabriel Schulhof PR-URL: #22932

rvagg · 2018-09-20T13:20:23Z

Is this only useful for isolated performance hacks? I'm trying to think of a use-case for it and can't, beyond the kinds of things that go in to util.inspect() as mentioned. Seems like an intentional leak on an abstraction that isn't intended to be leaky. Not a criticism, I'm just puzzled.

refack · 2018-09-20T13:49:26Z

Seems like an intentional leak on an abstraction that isn't intended to be leaky.

> var x= new Boolean()
> x
[Boolean: false]
> var y = false
> y
false
> typeof x
'object'
> typeof y
'boolean'
> x === y
false

I believe it's just an aggregate of checks already available in the language. But yeah, util and util.inspect provide abstraction breaking footguns, but they are explicit about it.

The util.inspect() method returns a string representation of object that is intended for debugging. The output of util.inspect may change at any time and should not be depended upon programmatically.

Please note that util.inspect() is a synchronous method that is mainly intended as a debugging tool. Some input values can have a significant performance overhead that can block the event loop. Use this function with care and never in a hot code path.

jdalton · 2018-09-20T15:23:45Z

As a utility lib author this method is exciting because I so run into a need for this kind of check (equality checks, cloning, merging, etc) and would rather defer to an environment builtin when possible.

BridgeAR · 2018-09-20T15:35:37Z

I did not implement it for performance reasons in the first place. I mainly want to have a utility function that makes sure I know if a variable is a boxed primitive or not. No matter what primitive it is. Otherwise I have a bloated code where I have to go through each boxed primitive manually / write an abstraction for it.

Doing it in core seemed the best way of doing it because we do less boundary crossings and it fits well into all the other util.types functions. We have something similar with IsAnyArrayBuffer.

rvagg · 2018-09-20T22:39:30Z

OK, I get it, thanks for the insight folks!

ljharb · 2018-09-21T06:24:08Z

For those interested, I ended up making a package for this: https://www.npmjs.com/package/is-boxed-primitive

util: add util.types.isBoxedPrimitive

1d9a02d

Checking all boxed primitives individually requires to cross the C++ barrier multiple times besides being more complicated than just a single check.

BridgeAR requested a review from addaleax August 31, 2018 13:41

nodejs-github-bot added the c++ Issues and PRs that require attention from people who are familiar with C++. label Aug 31, 2018

BridgeAR mentioned this pull request Aug 31, 2018

util: improve util inspect performance #22503

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Release proposal: v10.11.0 #22932

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util: add util.types.isBoxedPrimitive #22620

util: add util.types.isBoxedPrimitive #22620

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util: add util.types.isBoxedPrimitive #22620

util: add util.types.isBoxedPrimitive #22620

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